1 /*
2 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/castnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/castnode.hpp"
31 #include "opto/divnode.hpp"
32 #include "opto/loopnode.hpp"
33 #include "opto/matcher.hpp"
34 #include "opto/mulnode.hpp"
35 #include "opto/movenode.hpp"
36 #include "opto/opaquenode.hpp"
37 #include "opto/rootnode.hpp"
38 #include "opto/subnode.hpp"
39
40 //=============================================================================
41 //------------------------------split_thru_phi---------------------------------
42 // Split Node 'n' through merge point if there is enough win.
43 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
44 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
45 // ConvI2L may have type information on it which is unsafe to push up
46 // so disable this for now
47 return NULL;
48 }
49
50 // Splitting range check CastIIs through a loop induction Phi can
51 // cause new Phis to be created that are left unrelated to the loop
52 // induction Phi and prevent optimizations (vectorization)
53 if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check()) {
54 return NULL;
55 }
56
57 int wins = 0;
58 assert(!n->is_CFG(), "");
59 assert(region->is_Region(), "");
60
61 const Type* type = n->bottom_type();
62 const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
63 Node *phi;
64 if (t_oop != NULL && t_oop->is_known_instance_field()) {
65 int iid = t_oop->instance_id();
66 int index = C->get_alias_index(t_oop);
67 int offset = t_oop->offset();
68 phi = new PhiNode(region, type, NULL, iid, index, offset);
69 } else {
70 phi = PhiNode::make_blank(region, n);
71 }
72 uint old_unique = C->unique();
73 for (uint i = 1; i < region->req(); i++) {
74 Node *x;
75 Node* the_clone = NULL;
76 if (region->in(i) == C->top()) {
77 x = C->top(); // Dead path? Use a dead data op
78 } else {
79 x = n->clone(); // Else clone up the data op
80 the_clone = x; // Remember for possible deletion.
81 // Alter data node to use pre-phi inputs
82 if (n->in(0) == region)
83 x->set_req( 0, region->in(i) );
84 for (uint j = 1; j < n->req(); j++) {
85 Node *in = n->in(j);
86 if (in->is_Phi() && in->in(0) == region)
87 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
88 }
89 }
90 // Check for a 'win' on some paths
91 const Type *t = x->Value(&_igvn);
92
93 bool singleton = t->singleton();
94
95 // A TOP singleton indicates that there are no possible values incoming
96 // along a particular edge. In most cases, this is OK, and the Phi will
97 // be eliminated later in an Ideal call. However, we can't allow this to
98 // happen if the singleton occurs on loop entry, as the elimination of
99 // the PhiNode may cause the resulting node to migrate back to a previous
100 // loop iteration.
101 if (singleton && t == Type::TOP) {
102 // Is_Loop() == false does not confirm the absence of a loop (e.g., an
103 // irreducible loop may not be indicated by an affirmative is_Loop());
104 // therefore, the only top we can split thru a phi is on a backedge of
105 // a loop.
106 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
107 }
108
109 if (singleton) {
110 wins++;
111 x = ((PhaseGVN&)_igvn).makecon(t);
112 } else {
113 // We now call Identity to try to simplify the cloned node.
114 // Note that some Identity methods call phase->type(this).
115 // Make sure that the type array is big enough for
116 // our new node, even though we may throw the node away.
117 // (Note: This tweaking with igvn only works because x is a new node.)
118 _igvn.set_type(x, t);
119 // If x is a TypeNode, capture any more-precise type permanently into Node
120 // otherwise it will be not updated during igvn->transform since
121 // igvn->type(x) is set to x->Value() already.
122 x->raise_bottom_type(t);
123 Node *y = x->Identity(&_igvn);
124 if (y != x) {
125 wins++;
126 x = y;
127 } else {
128 y = _igvn.hash_find(x);
129 if (y) {
130 wins++;
131 x = y;
132 } else {
133 // Else x is a new node we are keeping
134 // We do not need register_new_node_with_optimizer
135 // because set_type has already been called.
136 _igvn._worklist.push(x);
137 }
138 }
139 }
140 if (x != the_clone && the_clone != NULL)
141 _igvn.remove_dead_node(the_clone);
142 phi->set_req( i, x );
143 }
144 // Too few wins?
145 if (wins <= policy) {
146 _igvn.remove_dead_node(phi);
147 return NULL;
148 }
149
150 // Record Phi
151 register_new_node( phi, region );
152
153 for (uint i2 = 1; i2 < phi->req(); i2++) {
154 Node *x = phi->in(i2);
155 // If we commoned up the cloned 'x' with another existing Node,
156 // the existing Node picks up a new use. We need to make the
157 // existing Node occur higher up so it dominates its uses.
158 Node *old_ctrl;
159 IdealLoopTree *old_loop;
160
161 if (x->is_Con()) {
162 // Constant's control is always root.
163 set_ctrl(x, C->root());
164 continue;
165 }
166 // The occasional new node
167 if (x->_idx >= old_unique) { // Found a new, unplaced node?
168 old_ctrl = NULL;
169 old_loop = NULL; // Not in any prior loop
170 } else {
171 old_ctrl = get_ctrl(x);
172 old_loop = get_loop(old_ctrl); // Get prior loop
173 }
174 // New late point must dominate new use
175 Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
176 if (new_ctrl == old_ctrl) // Nothing is changed
177 continue;
178
179 IdealLoopTree *new_loop = get_loop(new_ctrl);
180
181 // Don't move x into a loop if its uses are
182 // outside of loop. Otherwise x will be cloned
183 // for each use outside of this loop.
184 IdealLoopTree *use_loop = get_loop(region);
185 if (!new_loop->is_member(use_loop) &&
186 (old_loop == NULL || !new_loop->is_member(old_loop))) {
187 // Take early control, later control will be recalculated
188 // during next iteration of loop optimizations.
189 new_ctrl = get_early_ctrl(x);
190 new_loop = get_loop(new_ctrl);
191 }
192 // Set new location
193 set_ctrl(x, new_ctrl);
194 // If changing loop bodies, see if we need to collect into new body
195 if (old_loop != new_loop) {
196 if (old_loop && !old_loop->_child)
197 old_loop->_body.yank(x);
198 if (!new_loop->_child)
199 new_loop->_body.push(x); // Collect body info
200 }
201 }
202
203 return phi;
204 }
205
206 //------------------------------dominated_by------------------------------------
207 // Replace the dominated test with an obvious true or false. Place it on the
208 // IGVN worklist for later cleanup. Move control-dependent data Nodes on the
209 // live path up to the dominating control.
210 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
211 if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
212
213 // prevdom is the dominating projection of the dominating test.
214 assert( iff->is_If(), "" );
215 assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
216 int pop = prevdom->Opcode();
217 assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
218 if (flip) {
219 if (pop == Op_IfTrue)
220 pop = Op_IfFalse;
221 else
222 pop = Op_IfTrue;
223 }
224 // 'con' is set to true or false to kill the dominated test.
225 Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
226 set_ctrl(con, C->root()); // Constant gets a new use
227 // Hack the dominated test
228 _igvn.replace_input_of(iff, 1, con);
229
230 // If I dont have a reachable TRUE and FALSE path following the IfNode then
231 // I can assume this path reaches an infinite loop. In this case it's not
232 // important to optimize the data Nodes - either the whole compilation will
233 // be tossed or this path (and all data Nodes) will go dead.
234 if (iff->outcnt() != 2) return;
235
236 // Make control-dependent data Nodes on the live path (path that will remain
237 // once the dominated IF is removed) become control-dependent on the
238 // dominating projection.
239 Node* dp = iff->as_If()->proj_out(pop == Op_IfTrue);
240
241 // Loop predicates may have depending checks which should not
242 // be skipped. For example, range check predicate has two checks
243 // for lower and upper bounds.
244 if (dp == NULL)
245 return;
246
247 ProjNode* dp_proj = dp->as_Proj();
248 ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
249 if (exclude_loop_predicate &&
250 (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
251 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
252 // If this is a range check (IfNode::is_range_check), do not
253 // reorder because Compile::allow_range_check_smearing might have
254 // changed the check.
255 return; // Let IGVN transformation change control dependence.
256 }
257
258 IdealLoopTree *old_loop = get_loop(dp);
259
260 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
261 Node* cd = dp->fast_out(i); // Control-dependent node
262 if (cd->depends_only_on_test()) {
263 assert(cd->in(0) == dp, "");
264 _igvn.replace_input_of(cd, 0, prevdom);
265 set_early_ctrl(cd);
266 IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
267 if (old_loop != new_loop) {
268 if (!old_loop->_child) old_loop->_body.yank(cd);
269 if (!new_loop->_child) new_loop->_body.push(cd);
270 }
271 --i;
272 --imax;
273 }
274 }
275 }
276
277 //------------------------------has_local_phi_input----------------------------
278 // Return TRUE if 'n' has Phi inputs from its local block and no other
279 // block-local inputs (all non-local-phi inputs come from earlier blocks)
280 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
281 Node *n_ctrl = get_ctrl(n);
282 // See if some inputs come from a Phi in this block, or from before
283 // this block.
284 uint i;
285 for( i = 1; i < n->req(); i++ ) {
286 Node *phi = n->in(i);
287 if( phi->is_Phi() && phi->in(0) == n_ctrl )
288 break;
289 }
290 if( i >= n->req() )
291 return NULL; // No Phi inputs; nowhere to clone thru
292
293 // Check for inputs created between 'n' and the Phi input. These
294 // must split as well; they have already been given the chance
295 // (courtesy of a post-order visit) and since they did not we must
296 // recover the 'cost' of splitting them by being very profitable
297 // when splitting 'n'. Since this is unlikely we simply give up.
298 for( i = 1; i < n->req(); i++ ) {
299 Node *m = n->in(i);
300 if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
301 // We allow the special case of AddP's with no local inputs.
302 // This allows us to split-up address expressions.
303 if (m->is_AddP() &&
304 get_ctrl(m->in(2)) != n_ctrl &&
305 get_ctrl(m->in(3)) != n_ctrl) {
306 // Move the AddP up to dominating point
307 set_ctrl_and_loop(m, find_non_split_ctrl(idom(n_ctrl)));
308 continue;
309 }
310 return NULL;
311 }
312 }
313
314 return n_ctrl;
315 }
316
317 //------------------------------remix_address_expressions----------------------
318 // Rework addressing expressions to get the most loop-invariant stuff
319 // moved out. We'd like to do all associative operators, but it's especially
320 // important (common) to do address expressions.
321 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
322 if (!has_ctrl(n)) return NULL;
323 Node *n_ctrl = get_ctrl(n);
324 IdealLoopTree *n_loop = get_loop(n_ctrl);
325
326 // See if 'n' mixes loop-varying and loop-invariant inputs and
327 // itself is loop-varying.
328
329 // Only interested in binary ops (and AddP)
330 if( n->req() < 3 || n->req() > 4 ) return NULL;
331
332 Node *n1_ctrl = get_ctrl(n->in( 1));
333 Node *n2_ctrl = get_ctrl(n->in( 2));
334 Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
335 IdealLoopTree *n1_loop = get_loop( n1_ctrl );
336 IdealLoopTree *n2_loop = get_loop( n2_ctrl );
337 IdealLoopTree *n3_loop = get_loop( n3_ctrl );
338
339 // Does one of my inputs spin in a tighter loop than self?
340 if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
341 (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
342 (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
343 return NULL; // Leave well enough alone
344
345 // Is at least one of my inputs loop-invariant?
346 if( n1_loop == n_loop &&
347 n2_loop == n_loop &&
348 n3_loop == n_loop )
349 return NULL; // No loop-invariant inputs
350
351
352 int n_op = n->Opcode();
353
354 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
355 if( n_op == Op_LShiftI ) {
356 // Scale is loop invariant
357 Node *scale = n->in(2);
358 Node *scale_ctrl = get_ctrl(scale);
359 IdealLoopTree *scale_loop = get_loop(scale_ctrl );
360 if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
361 return NULL;
362 const TypeInt *scale_t = scale->bottom_type()->isa_int();
363 if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
364 return NULL; // Dont bother with byte/short masking
365 // Add must vary with loop (else shift would be loop-invariant)
366 Node *add = n->in(1);
367 Node *add_ctrl = get_ctrl(add);
368 IdealLoopTree *add_loop = get_loop(add_ctrl);
369 //assert( n_loop == add_loop, "" );
370 if( n_loop != add_loop ) return NULL; // happens w/ evil ZKM loops
371
372 // Convert I-V into I+ (0-V); same for V-I
373 if( add->Opcode() == Op_SubI &&
374 _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
375 Node *zero = _igvn.intcon(0);
376 set_ctrl(zero, C->root());
377 Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
378 register_new_node( neg, get_ctrl(add->in(2) ) );
379 add = new AddINode( add->in(1), neg );
380 register_new_node( add, add_ctrl );
381 }
382 if( add->Opcode() != Op_AddI ) return NULL;
383 // See if one add input is loop invariant
384 Node *add_var = add->in(1);
385 Node *add_var_ctrl = get_ctrl(add_var);
386 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
387 Node *add_invar = add->in(2);
388 Node *add_invar_ctrl = get_ctrl(add_invar);
389 IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
390 if( add_var_loop == n_loop ) {
391 } else if( add_invar_loop == n_loop ) {
392 // Swap to find the invariant part
393 add_invar = add_var;
394 add_invar_ctrl = add_var_ctrl;
395 add_invar_loop = add_var_loop;
396 add_var = add->in(2);
397 Node *add_var_ctrl = get_ctrl(add_var);
398 IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
399 } else // Else neither input is loop invariant
400 return NULL;
401 if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
402 return NULL; // No invariant part of the add?
403
404 // Yes! Reshape address expression!
405 Node *inv_scale = new LShiftINode( add_invar, scale );
406 Node *inv_scale_ctrl =
407 dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
408 add_invar_ctrl : scale_ctrl;
409 register_new_node( inv_scale, inv_scale_ctrl );
410 Node *var_scale = new LShiftINode( add_var, scale );
411 register_new_node( var_scale, n_ctrl );
412 Node *var_add = new AddINode( var_scale, inv_scale );
413 register_new_node( var_add, n_ctrl );
414 _igvn.replace_node( n, var_add );
415 return var_add;
416 }
417
418 // Replace (I+V) with (V+I)
419 if( n_op == Op_AddI ||
420 n_op == Op_AddL ||
421 n_op == Op_AddF ||
422 n_op == Op_AddD ||
423 n_op == Op_MulI ||
424 n_op == Op_MulL ||
425 n_op == Op_MulF ||
426 n_op == Op_MulD ) {
427 if( n2_loop == n_loop ) {
428 assert( n1_loop != n_loop, "" );
429 n->swap_edges(1, 2);
430 }
431 }
432
433 // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
434 // but not if I2 is a constant.
435 if( n_op == Op_AddP ) {
436 if( n2_loop == n_loop && n3_loop != n_loop ) {
437 if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
438 Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
439 Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
440 IdealLoopTree *n22loop = get_loop( n22_ctrl );
441 IdealLoopTree *n23_loop = get_loop( n23_ctrl );
442 if( n22loop != n_loop && n22loop->is_member(n_loop) &&
443 n23_loop == n_loop ) {
444 Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
445 // Stuff new AddP in the loop preheader
446 register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
447 Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
448 register_new_node( add2, n_ctrl );
449 _igvn.replace_node( n, add2 );
450 return add2;
451 }
452 }
453 }
454
455 // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
456 if (n2_loop != n_loop && n3_loop == n_loop) {
457 if (n->in(3)->Opcode() == Op_AddX) {
458 Node *V = n->in(3)->in(1);
459 Node *I = n->in(3)->in(2);
460 if (is_member(n_loop,get_ctrl(V))) {
461 } else {
462 Node *tmp = V; V = I; I = tmp;
463 }
464 if (!is_member(n_loop,get_ctrl(I))) {
465 Node *add1 = new AddPNode(n->in(1), n->in(2), I);
466 // Stuff new AddP in the loop preheader
467 register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
468 Node *add2 = new AddPNode(n->in(1), add1, V);
469 register_new_node(add2, n_ctrl);
470 _igvn.replace_node(n, add2);
471 return add2;
472 }
473 }
474 }
475 }
476
477 return NULL;
478 }
479
480 //------------------------------conditional_move-------------------------------
481 // Attempt to replace a Phi with a conditional move. We have some pretty
482 // strict profitability requirements. All Phis at the merge point must
483 // be converted, so we can remove the control flow. We need to limit the
484 // number of c-moves to a small handful. All code that was in the side-arms
485 // of the CFG diamond is now speculatively executed. This code has to be
486 // "cheap enough". We are pretty much limited to CFG diamonds that merge
487 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
488 Node *PhaseIdealLoop::conditional_move( Node *region ) {
489
490 assert(region->is_Region(), "sanity check");
491 if (region->req() != 3) return NULL;
492
493 // Check for CFG diamond
494 Node *lp = region->in(1);
495 Node *rp = region->in(2);
496 if (!lp || !rp) return NULL;
497 Node *lp_c = lp->in(0);
498 if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
499 IfNode *iff = lp_c->as_If();
500
501 // Check for ops pinned in an arm of the diamond.
502 // Can't remove the control flow in this case
503 if (lp->outcnt() > 1) return NULL;
504 if (rp->outcnt() > 1) return NULL;
505
506 IdealLoopTree* r_loop = get_loop(region);
507 assert(r_loop == get_loop(iff), "sanity");
508 // Always convert to CMOVE if all results are used only outside this loop.
509 bool used_inside_loop = (r_loop == _ltree_root);
510
511 // Check profitability
512 int cost = 0;
513 int phis = 0;
514 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
515 Node *out = region->fast_out(i);
516 if (!out->is_Phi()) continue; // Ignore other control edges, etc
517 phis++;
518 PhiNode* phi = out->as_Phi();
519 BasicType bt = phi->type()->basic_type();
520 switch (bt) {
521 case T_DOUBLE:
522 if (C->use_cmove()) {
523 continue; //TODO: maybe we want to add some cost
524 }
525 case T_FLOAT: {
526 cost += Matcher::float_cmove_cost(); // Could be very expensive
527 break;
528 }
529 case T_LONG: {
530 cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
531 }
532 case T_INT: // These all CMOV fine
533 case T_ADDRESS: { // (RawPtr)
534 cost++;
535 break;
536 }
537 case T_NARROWOOP: // Fall through
538 case T_OBJECT: { // Base oops are OK, but not derived oops
539 const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
540 // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
541 // CMOVE'd derived pointer? It's a CMOVE'd derived base. Thus
542 // CMOVE'ing a derived pointer requires we also CMOVE the base. If we
543 // have a Phi for the base here that we convert to a CMOVE all is well
544 // and good. But if the base is dead, we'll not make a CMOVE. Later
545 // the allocator will have to produce a base by creating a CMOVE of the
546 // relevant bases. This puts the allocator in the business of
547 // manufacturing expensive instructions, generally a bad plan.
548 // Just Say No to Conditionally-Moved Derived Pointers.
549 if (tp && tp->offset() != 0)
550 return NULL;
551 cost++;
552 break;
553 }
554 default:
555 return NULL; // In particular, can't do memory or I/O
556 }
557 // Add in cost any speculative ops
558 for (uint j = 1; j < region->req(); j++) {
559 Node *proj = region->in(j);
560 Node *inp = phi->in(j);
561 if (get_ctrl(inp) == proj) { // Found local op
562 cost++;
563 // Check for a chain of dependent ops; these will all become
564 // speculative in a CMOV.
565 for (uint k = 1; k < inp->req(); k++)
566 if (get_ctrl(inp->in(k)) == proj)
567 cost += ConditionalMoveLimit; // Too much speculative goo
568 }
569 }
570 // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
571 // This will likely Split-If, a higher-payoff operation.
572 for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
573 Node* use = phi->fast_out(k);
574 if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
575 cost += ConditionalMoveLimit;
576 // Is there a use inside the loop?
577 // Note: check only basic types since CMoveP is pinned.
578 if (!used_inside_loop && is_java_primitive(bt)) {
579 IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
580 if (r_loop == u_loop || r_loop->is_member(u_loop)) {
581 used_inside_loop = true;
582 }
583 }
584 }
585 }//for
586 Node* bol = iff->in(1);
587 assert(bol->Opcode() == Op_Bool, "");
588 int cmp_op = bol->in(1)->Opcode();
589 // It is expensive to generate flags from a float compare.
590 // Avoid duplicated float compare.
591 if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
592
593 float infrequent_prob = PROB_UNLIKELY_MAG(3);
594 // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
595 if (used_inside_loop) {
596 if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
597
598 // BlockLayoutByFrequency optimization moves infrequent branch
599 // from hot path. No point in CMOV'ing in such case (110 is used
600 // instead of 100 to take into account not exactness of float value).
601 if (BlockLayoutByFrequency) {
602 infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
603 }
604 }
605 // Check for highly predictable branch. No point in CMOV'ing if
606 // we are going to predict accurately all the time.
607 if (C->use_cmove() && cmp_op == Op_CmpD) ;//keep going
608 else if (iff->_prob < infrequent_prob ||
609 iff->_prob > (1.0f - infrequent_prob))
610 return NULL;
611
612 // --------------
613 // Now replace all Phis with CMOV's
614 Node *cmov_ctrl = iff->in(0);
615 uint flip = (lp->Opcode() == Op_IfTrue);
616 while (1) {
617 PhiNode* phi = NULL;
618 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
619 Node *out = region->fast_out(i);
620 if (out->is_Phi()) {
621 phi = out->as_Phi();
622 break;
623 }
624 }
625 if (phi == NULL) break;
626 if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
627 // Move speculative ops
628 for (uint j = 1; j < region->req(); j++) {
629 Node *proj = region->in(j);
630 Node *inp = phi->in(j);
631 if (get_ctrl(inp) == proj) { // Found local op
632 #ifndef PRODUCT
633 if (PrintOpto && VerifyLoopOptimizations) {
634 tty->print(" speculate: ");
635 inp->dump();
636 }
637 #endif
638 set_ctrl(inp, cmov_ctrl);
639 }
640 }
641 Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
642 register_new_node( cmov, cmov_ctrl );
643 _igvn.replace_node( phi, cmov );
644 #ifndef PRODUCT
645 if (TraceLoopOpts) {
646 tty->print("CMOV ");
647 r_loop->dump_head();
648 if (Verbose) {
649 bol->in(1)->dump(1);
650 cmov->dump(1);
651 }
652 }
653 if (VerifyLoopOptimizations) verify();
654 #endif
655 }
656
657 // The useless CFG diamond will fold up later; see the optimization in
658 // RegionNode::Ideal.
659 _igvn._worklist.push(region);
660
661 return iff->in(1);
662 }
663
664 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
665 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
666 Node* u = m->fast_out(i);
667 if (u->is_CFG()) {
668 if (u->Opcode() == Op_NeverBranch) {
669 u = ((NeverBranchNode*)u)->proj_out(0);
670 enqueue_cfg_uses(u, wq);
671 } else {
672 wq.push(u);
673 }
674 }
675 }
676 }
677
678 // Try moving a store out of a loop, right before the loop
679 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
680 // Store has to be first in the loop body
681 IdealLoopTree *n_loop = get_loop(n_ctrl);
682 if (n->is_Store() && n_loop != _ltree_root && n_loop->is_loop() && n->in(0) != NULL) {
683 Node* address = n->in(MemNode::Address);
684 Node* value = n->in(MemNode::ValueIn);
685 Node* mem = n->in(MemNode::Memory);
686 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
687 IdealLoopTree* value_loop = get_loop(get_ctrl(value));
688
689 // - address and value must be loop invariant
690 // - memory must be a memory Phi for the loop
691 // - Store must be the only store on this memory slice in the
692 // loop: if there's another store following this one then value
693 // written at iteration i by the second store could be overwritten
694 // at iteration i+n by the first store: it's not safe to move the
695 // first store out of the loop
696 // - nothing must observe the memory Phi: it guarantees no read
697 // before the store, we are also guaranteed the store post
698 // dominates the loop head (ignoring a possible early
699 // exit). Otherwise there would be extra Phi involved between the
700 // loop's Phi and the store.
701 // - there must be no early exit from the loop before the Store
702 // (such an exit most of the time would be an extra use of the
703 // memory Phi but sometimes is a bottom memory Phi that takes the
704 // store as input).
705
706 if (!n_loop->is_member(address_loop) &&
707 !n_loop->is_member(value_loop) &&
708 mem->is_Phi() && mem->in(0) == n_loop->_head &&
709 mem->outcnt() == 1 &&
710 mem->in(LoopNode::LoopBackControl) == n) {
711
712 assert(n_loop->_tail != NULL, "need a tail");
713 assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
714
715 // Verify that there's no early exit of the loop before the store.
716 bool ctrl_ok = false;
717 {
718 // Follow control from loop head until n, we exit the loop or
719 // we reach the tail
720 ResourceMark rm;
721 Unique_Node_List wq;
722 wq.push(n_loop->_head);
723
724 for (uint next = 0; next < wq.size(); ++next) {
725 Node *m = wq.at(next);
726 if (m == n->in(0)) {
727 ctrl_ok = true;
728 continue;
729 }
730 assert(!has_ctrl(m), "should be CFG");
731 if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
732 ctrl_ok = false;
733 break;
734 }
735 enqueue_cfg_uses(m, wq);
736 if (wq.size() > 10) {
737 ctrl_ok = false;
738 break;
739 }
740 }
741 }
742 if (ctrl_ok) {
743 // move the Store
744 _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
745 _igvn.replace_input_of(n, 0, n_loop->_head->in(LoopNode::EntryControl));
746 _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
747 // Disconnect the phi now. An empty phi can confuse other
748 // optimizations in this pass of loop opts.
749 _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
750 n_loop->_body.yank(mem);
751
752 IdealLoopTree* new_loop = get_loop(n->in(0));
753 set_ctrl_and_loop(n, n->in(0));
754
755 return n;
756 }
757 }
758 }
759 return NULL;
760 }
761
762 // Try moving a store out of a loop, right after the loop
763 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
764 if (n->is_Store() && n->in(0) != NULL) {
765 Node *n_ctrl = get_ctrl(n);
766 IdealLoopTree *n_loop = get_loop(n_ctrl);
767 // Store must be in a loop
768 if (n_loop != _ltree_root && !n_loop->_irreducible) {
769 Node* address = n->in(MemNode::Address);
770 Node* value = n->in(MemNode::ValueIn);
771 IdealLoopTree* address_loop = get_loop(get_ctrl(address));
772 // address must be loop invariant
773 if (!n_loop->is_member(address_loop)) {
774 // Store must be last on this memory slice in the loop and
775 // nothing in the loop must observe it
776 Node* phi = NULL;
777 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
778 Node* u = n->fast_out(i);
779 if (has_ctrl(u)) { // control use?
780 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
781 if (!n_loop->is_member(u_loop)) {
782 continue;
783 }
784 if (u->is_Phi() && u->in(0) == n_loop->_head) {
785 assert(_igvn.type(u) == Type::MEMORY, "bad phi");
786 // multiple phis on the same slice are possible
787 if (phi != NULL) {
788 return;
789 }
790 phi = u;
791 continue;
792 }
793 }
794 return;
795 }
796 if (phi != NULL) {
797 // Nothing in the loop before the store (next iteration)
798 // must observe the stored value
799 bool mem_ok = true;
800 {
801 ResourceMark rm;
802 Unique_Node_List wq;
803 wq.push(phi);
804 for (uint next = 0; next < wq.size() && mem_ok; ++next) {
805 Node *m = wq.at(next);
806 for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
807 Node* u = m->fast_out(i);
808 if (u->is_Store() || u->is_Phi()) {
809 if (u != n) {
810 wq.push(u);
811 mem_ok = (wq.size() <= 10);
812 }
813 } else {
814 mem_ok = false;
815 break;
816 }
817 }
818 }
819 }
820 if (mem_ok) {
821 // Move the Store out of the loop creating clones along
822 // all paths out of the loop that observe the stored value
823 _igvn.rehash_node_delayed(phi);
824 int count = phi->replace_edge(n, n->in(MemNode::Memory));
825 assert(count > 0, "inconsistent phi");
826 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
827 Node* u = n->fast_out(i);
828 Node* c = get_ctrl(u);
829
830 if (u->is_Phi()) {
831 c = u->in(0)->in(u->find_edge(n));
832 }
833 IdealLoopTree *u_loop = get_loop(c);
834 assert (!n_loop->is_member(u_loop), "only the phi should have been a use in the loop");
835 while(true) {
836 Node* next_c = find_non_split_ctrl(idom(c));
837 if (n_loop->is_member(get_loop(next_c))) {
838 break;
839 }
840 c = next_c;
841 }
842
843 Node* st = n->clone();
844 st->set_req(0, c);
845 _igvn.register_new_node_with_optimizer(st);
846
847 set_ctrl(st, c);
848 IdealLoopTree* new_loop = get_loop(c);
849 assert(new_loop != n_loop, "should be moved out of loop");
850 if (new_loop->_child == NULL) new_loop->_body.push(st);
851
852 _igvn.replace_input_of(u, u->find_edge(n), st);
853 --imax;
854 --i;
855 }
856
857
858 assert(n->outcnt() == 0, "all uses should be gone");
859 _igvn.replace_input_of(n, MemNode::Memory, C->top());
860 // Disconnect the phi now. An empty phi can confuse other
861 // optimizations in this pass of loop opts..
862 if (phi->in(LoopNode::LoopBackControl) == phi) {
863 _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
864 n_loop->_body.yank(phi);
865 }
866 }
867 }
868 }
869 }
870 }
871 }
872
873 //------------------------------split_if_with_blocks_pre-----------------------
874 // Do the real work in a non-recursive function. Data nodes want to be
875 // cloned in the pre-order so they can feed each other nicely.
876 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
877 // Cloning these guys is unlikely to win
878 int n_op = n->Opcode();
879 if( n_op == Op_MergeMem ) return n;
880 if( n->is_Proj() ) return n;
881 // Do not clone-up CmpFXXX variations, as these are always
882 // followed by a CmpI
883 if( n->is_Cmp() ) return n;
884 // Attempt to use a conditional move instead of a phi/branch
885 if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
886 Node *cmov = conditional_move( n );
887 if( cmov ) return cmov;
888 }
889 if( n->is_CFG() || n->is_LoadStore() )
890 return n;
891 if( n_op == Op_Opaque1 || // Opaque nodes cannot be mod'd
892 n_op == Op_Opaque2 ) {
893 if( !C->major_progress() ) // If chance of no more loop opts...
894 _igvn._worklist.push(n); // maybe we'll remove them
895 return n;
896 }
897
898 if( n->is_Con() ) return n; // No cloning for Con nodes
899
900 Node *n_ctrl = get_ctrl(n);
901 if( !n_ctrl ) return n; // Dead node
902
903 Node* res = try_move_store_before_loop(n, n_ctrl);
904 if (res != NULL) {
905 return n;
906 }
907
908 // Attempt to remix address expressions for loop invariants
909 Node *m = remix_address_expressions( n );
910 if( m ) return m;
911
912 if (n->is_ConstraintCast()) {
913 Node* dom_cast = n->as_ConstraintCast()->dominating_cast(this);
914 if (dom_cast != NULL) {
915 _igvn.replace_node(n, dom_cast);
916 return dom_cast;
917 }
918 }
919
920 // Determine if the Node has inputs from some local Phi.
921 // Returns the block to clone thru.
922 Node *n_blk = has_local_phi_input( n );
923 if( !n_blk ) return n;
924
925 // Do not clone the trip counter through on a CountedLoop
926 // (messes up the canonical shape).
927 if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
928
929 // Check for having no control input; not pinned. Allow
930 // dominating control.
931 if (n->in(0)) {
932 Node *dom = idom(n_blk);
933 if (dom_lca(n->in(0), dom) != n->in(0)) {
934 return n;
935 }
936 }
937 // Policy: when is it profitable. You must get more wins than
938 // policy before it is considered profitable. Policy is usually 0,
939 // so 1 win is considered profitable. Big merges will require big
940 // cloning, so get a larger policy.
941 int policy = n_blk->req() >> 2;
942
943 // If the loop is a candidate for range check elimination,
944 // delay splitting through it's phi until a later loop optimization
945 if (n_blk->is_CountedLoop()) {
946 IdealLoopTree *lp = get_loop(n_blk);
947 if (lp && lp->_rce_candidate) {
948 return n;
949 }
950 }
951
952 // Use same limit as split_if_with_blocks_post
953 if( C->live_nodes() > 35000 ) return n; // Method too big
954
955 // Split 'n' through the merge point if it is profitable
956 Node *phi = split_thru_phi( n, n_blk, policy );
957 if (!phi) return n;
958
959 // Found a Phi to split thru!
960 // Replace 'n' with the new phi
961 _igvn.replace_node( n, phi );
962 // Moved a load around the loop, 'en-registering' something.
963 if (n_blk->is_Loop() && n->is_Load() &&
964 !phi->in(LoopNode::LoopBackControl)->is_Load())
965 C->set_major_progress();
966
967 return phi;
968 }
969
970 static bool merge_point_too_heavy(Compile* C, Node* region) {
971 // Bail out if the region and its phis have too many users.
972 int weight = 0;
973 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
974 weight += region->fast_out(i)->outcnt();
975 }
976 int nodes_left = C->max_node_limit() - C->live_nodes();
977 if (weight * 8 > nodes_left) {
978 if (PrintOpto) {
979 tty->print_cr("*** Split-if bails out: %d nodes, region weight %d", C->unique(), weight);
980 }
981 return true;
982 } else {
983 return false;
984 }
985 }
986
987 static bool merge_point_safe(Node* region) {
988 // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
989 // having a PhiNode input. This sidesteps the dangerous case where the split
990 // ConvI2LNode may become TOP if the input Value() does not
991 // overlap the ConvI2L range, leaving a node which may not dominate its
992 // uses.
993 // A better fix for this problem can be found in the BugTraq entry, but
994 // expediency for Mantis demands this hack.
995 // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
996 // split_if_with_blocks from splitting a block because we could not move around
997 // the FastLockNode.
998 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
999 Node* n = region->fast_out(i);
1000 if (n->is_Phi()) {
1001 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1002 Node* m = n->fast_out(j);
1003 if (m->is_FastLock())
1004 return false;
1005 #ifdef _LP64
1006 if (m->Opcode() == Op_ConvI2L)
1007 return false;
1008 if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1009 return false;
1010 }
1011 #endif
1012 }
1013 }
1014 }
1015 return true;
1016 }
1017
1018
1019 //------------------------------place_near_use---------------------------------
1020 // Place some computation next to use but not inside inner loops.
1021 // For inner loop uses move it to the preheader area.
1022 Node *PhaseIdealLoop::place_near_use( Node *useblock ) const {
1023 IdealLoopTree *u_loop = get_loop( useblock );
1024 return (u_loop->_irreducible || u_loop->_child)
1025 ? useblock
1026 : u_loop->_head->in(LoopNode::EntryControl);
1027 }
1028
1029
1030 //------------------------------split_if_with_blocks_post----------------------
1031 // Do the real work in a non-recursive function. CFG hackery wants to be
1032 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1033 // info.
1034 void PhaseIdealLoop::split_if_with_blocks_post( Node *n ) {
1035
1036 // Cloning Cmp through Phi's involves the split-if transform.
1037 // FastLock is not used by an If
1038 if( n->is_Cmp() && !n->is_FastLock() ) {
1039 if( C->live_nodes() > 35000 ) return; // Method too big
1040
1041 // Do not do 'split-if' if irreducible loops are present.
1042 if( _has_irreducible_loops )
1043 return;
1044
1045 Node *n_ctrl = get_ctrl(n);
1046 // Determine if the Node has inputs from some local Phi.
1047 // Returns the block to clone thru.
1048 Node *n_blk = has_local_phi_input( n );
1049 if( n_blk != n_ctrl ) return;
1050
1051 if( merge_point_too_heavy(C, n_ctrl) )
1052 return;
1053
1054 if( n->outcnt() != 1 ) return; // Multiple bool's from 1 compare?
1055 Node *bol = n->unique_out();
1056 assert( bol->is_Bool(), "expect a bool here" );
1057 if( bol->outcnt() != 1 ) return;// Multiple branches from 1 compare?
1058 Node *iff = bol->unique_out();
1059
1060 // Check some safety conditions
1061 if( iff->is_If() ) { // Classic split-if?
1062 if( iff->in(0) != n_ctrl ) return; // Compare must be in same blk as if
1063 } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1064 // Can't split CMove with different control edge.
1065 if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) return;
1066 if( get_ctrl(iff->in(2)) == n_ctrl ||
1067 get_ctrl(iff->in(3)) == n_ctrl )
1068 return; // Inputs not yet split-up
1069 if ( get_loop(n_ctrl) != get_loop(get_ctrl(iff)) ) {
1070 return; // Loop-invar test gates loop-varying CMOVE
1071 }
1072 } else {
1073 return; // some other kind of node, such as an Allocate
1074 }
1075
1076 // Do not do 'split-if' if some paths are dead. First do dead code
1077 // elimination and then see if its still profitable.
1078 for( uint i = 1; i < n_ctrl->req(); i++ )
1079 if( n_ctrl->in(i) == C->top() )
1080 return;
1081
1082 // When is split-if profitable? Every 'win' on means some control flow
1083 // goes dead, so it's almost always a win.
1084 int policy = 0;
1085 // If trying to do a 'Split-If' at the loop head, it is only
1086 // profitable if the cmp folds up on BOTH paths. Otherwise we
1087 // risk peeling a loop forever.
1088
1089 // CNC - Disabled for now. Requires careful handling of loop
1090 // body selection for the cloned code. Also, make sure we check
1091 // for any input path not being in the same loop as n_ctrl. For
1092 // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1093 // because the alternative loop entry points won't be converted
1094 // into LoopNodes.
1095 IdealLoopTree *n_loop = get_loop(n_ctrl);
1096 for( uint j = 1; j < n_ctrl->req(); j++ )
1097 if( get_loop(n_ctrl->in(j)) != n_loop )
1098 return;
1099
1100 // Check for safety of the merge point.
1101 if( !merge_point_safe(n_ctrl) ) {
1102 return;
1103 }
1104
1105 // Split compare 'n' through the merge point if it is profitable
1106 Node *phi = split_thru_phi( n, n_ctrl, policy );
1107 if( !phi ) return;
1108
1109 // Found a Phi to split thru!
1110 // Replace 'n' with the new phi
1111 _igvn.replace_node( n, phi );
1112
1113 // Now split the bool up thru the phi
1114 Node *bolphi = split_thru_phi( bol, n_ctrl, -1 );
1115 guarantee(bolphi != NULL, "null boolean phi node");
1116
1117 _igvn.replace_node( bol, bolphi );
1118 assert( iff->in(1) == bolphi, "" );
1119
1120 if( bolphi->Value(&_igvn)->singleton() )
1121 return;
1122
1123 // Conditional-move? Must split up now
1124 if( !iff->is_If() ) {
1125 Node *cmovphi = split_thru_phi( iff, n_ctrl, -1 );
1126 _igvn.replace_node( iff, cmovphi );
1127 return;
1128 }
1129
1130 // Now split the IF
1131 do_split_if( iff );
1132 return;
1133 }
1134
1135 // Check for an IF ready to split; one that has its
1136 // condition codes input coming from a Phi at the block start.
1137 int n_op = n->Opcode();
1138
1139 // Check for an IF being dominated by another IF same test
1140 if (n_op == Op_If ||
1141 n_op == Op_RangeCheck) {
1142 Node *bol = n->in(1);
1143 uint max = bol->outcnt();
1144 // Check for same test used more than once?
1145 if (max > 1 && bol->is_Bool()) {
1146 // Search up IDOMs to see if this IF is dominated.
1147 Node *cutoff = get_ctrl(bol);
1148
1149 // Now search up IDOMs till cutoff, looking for a dominating test
1150 Node *prevdom = n;
1151 Node *dom = idom(prevdom);
1152 while (dom != cutoff) {
1153 if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1154 // Replace the dominated test with an obvious true or false.
1155 // Place it on the IGVN worklist for later cleanup.
1156 C->set_major_progress();
1157 dominated_by(prevdom, n, false, true);
1158 #ifndef PRODUCT
1159 if( VerifyLoopOptimizations ) verify();
1160 #endif
1161 return;
1162 }
1163 prevdom = dom;
1164 dom = idom(prevdom);
1165 }
1166 }
1167 }
1168
1169 // See if a shared loop-varying computation has no loop-varying uses.
1170 // Happens if something is only used for JVM state in uncommon trap exits,
1171 // like various versions of induction variable+offset. Clone the
1172 // computation per usage to allow it to sink out of the loop.
1173 if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1174 Node *n_ctrl = get_ctrl(n);
1175 IdealLoopTree *n_loop = get_loop(n_ctrl);
1176 if( n_loop != _ltree_root ) {
1177 DUIterator_Fast imax, i = n->fast_outs(imax);
1178 for (; i < imax; i++) {
1179 Node* u = n->fast_out(i);
1180 if( !has_ctrl(u) ) break; // Found control user
1181 IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1182 if( u_loop == n_loop ) break; // Found loop-varying use
1183 if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1184 if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1185 }
1186 bool did_break = (i < imax); // Did we break out of the previous loop?
1187 if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1188 Node *late_load_ctrl = NULL;
1189 if (n->is_Load()) {
1190 // If n is a load, get and save the result from get_late_ctrl(),
1191 // to be later used in calculating the control for n's clones.
1192 clear_dom_lca_tags();
1193 late_load_ctrl = get_late_ctrl(n, n_ctrl);
1194 }
1195 // If n is a load, and the late control is the same as the current
1196 // control, then the cloning of n is a pointless exercise, because
1197 // GVN will ensure that we end up where we started.
1198 if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1199 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1200 Node *u = n->last_out(j); // Clone private computation per use
1201 _igvn.rehash_node_delayed(u);
1202 Node *x = n->clone(); // Clone computation
1203 Node *x_ctrl = NULL;
1204 if( u->is_Phi() ) {
1205 // Replace all uses of normal nodes. Replace Phi uses
1206 // individually, so the separate Nodes can sink down
1207 // different paths.
1208 uint k = 1;
1209 while( u->in(k) != n ) k++;
1210 u->set_req( k, x );
1211 // x goes next to Phi input path
1212 x_ctrl = u->in(0)->in(k);
1213 --j;
1214 } else { // Normal use
1215 // Replace all uses
1216 for( uint k = 0; k < u->req(); k++ ) {
1217 if( u->in(k) == n ) {
1218 u->set_req( k, x );
1219 --j;
1220 }
1221 }
1222 x_ctrl = get_ctrl(u);
1223 }
1224
1225 // Find control for 'x' next to use but not inside inner loops.
1226 // For inner loop uses get the preheader area.
1227 x_ctrl = place_near_use(x_ctrl);
1228
1229 if (n->is_Load()) {
1230 // For loads, add a control edge to a CFG node outside of the loop
1231 // to force them to not combine and return back inside the loop
1232 // during GVN optimization (4641526).
1233 //
1234 // Because we are setting the actual control input, factor in
1235 // the result from get_late_ctrl() so we respect any
1236 // anti-dependences. (6233005).
1237 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1238
1239 // Don't allow the control input to be a CFG splitting node.
1240 // Such nodes should only have ProjNodes as outs, e.g. IfNode
1241 // should only have IfTrueNode and IfFalseNode (4985384).
1242 x_ctrl = find_non_split_ctrl(x_ctrl);
1243 assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1244
1245 x->set_req(0, x_ctrl);
1246 }
1247 register_new_node(x, x_ctrl);
1248
1249 // Some institutional knowledge is needed here: 'x' is
1250 // yanked because if the optimizer runs GVN on it all the
1251 // cloned x's will common up and undo this optimization and
1252 // be forced back in the loop. This is annoying because it
1253 // makes +VerifyOpto report false-positives on progress. I
1254 // tried setting control edges on the x's to force them to
1255 // not combine, but the matching gets worried when it tries
1256 // to fold a StoreP and an AddP together (as part of an
1257 // address expression) and the AddP and StoreP have
1258 // different controls.
1259 if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1260 }
1261 _igvn.remove_dead_node(n);
1262 }
1263 }
1264 }
1265 }
1266
1267 try_move_store_after_loop(n);
1268
1269 // Check for Opaque2's who's loop has disappeared - who's input is in the
1270 // same loop nest as their output. Remove 'em, they are no longer useful.
1271 if( n_op == Op_Opaque2 &&
1272 n->in(1) != NULL &&
1273 get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1274 _igvn.replace_node( n, n->in(1) );
1275 }
1276 }
1277
1278 //------------------------------split_if_with_blocks---------------------------
1279 // Check for aggressive application of 'split-if' optimization,
1280 // using basic block level info.
1281 void PhaseIdealLoop::split_if_with_blocks( VectorSet &visited, Node_Stack &nstack ) {
1282 Node *n = C->root();
1283 visited.set(n->_idx); // first, mark node as visited
1284 // Do pre-visit work for root
1285 n = split_if_with_blocks_pre( n );
1286 uint cnt = n->outcnt();
1287 uint i = 0;
1288 while (true) {
1289 // Visit all children
1290 if (i < cnt) {
1291 Node* use = n->raw_out(i);
1292 ++i;
1293 if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1294 // Now do pre-visit work for this use
1295 use = split_if_with_blocks_pre( use );
1296 nstack.push(n, i); // Save parent and next use's index.
1297 n = use; // Process all children of current use.
1298 cnt = use->outcnt();
1299 i = 0;
1300 }
1301 }
1302 else {
1303 // All of n's children have been processed, complete post-processing.
1304 if (cnt != 0 && !n->is_Con()) {
1305 assert(has_node(n), "no dead nodes");
1306 split_if_with_blocks_post( n );
1307 }
1308 if (nstack.is_empty()) {
1309 // Finished all nodes on stack.
1310 break;
1311 }
1312 // Get saved parent node and next use's index. Visit the rest of uses.
1313 n = nstack.node();
1314 cnt = n->outcnt();
1315 i = nstack.index();
1316 nstack.pop();
1317 }
1318 }
1319 }
1320
1321
1322 //=============================================================================
1323 //
1324 // C L O N E A L O O P B O D Y
1325 //
1326
1327 //------------------------------clone_iff--------------------------------------
1328 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1329 // "Nearly" because all Nodes have been cloned from the original in the loop,
1330 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1331 // through the Phi recursively, and return a Bool.
1332 BoolNode *PhaseIdealLoop::clone_iff( PhiNode *phi, IdealLoopTree *loop ) {
1333
1334 // Convert this Phi into a Phi merging Bools
1335 uint i;
1336 for( i = 1; i < phi->req(); i++ ) {
1337 Node *b = phi->in(i);
1338 if( b->is_Phi() ) {
1339 _igvn.replace_input_of(phi, i, clone_iff( b->as_Phi(), loop ));
1340 } else {
1341 assert( b->is_Bool(), "" );
1342 }
1343 }
1344
1345 Node *sample_bool = phi->in(1);
1346 Node *sample_cmp = sample_bool->in(1);
1347
1348 // Make Phis to merge the Cmp's inputs.
1349 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1350 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1351 for( i = 1; i < phi->req(); i++ ) {
1352 Node *n1 = phi->in(i)->in(1)->in(1);
1353 Node *n2 = phi->in(i)->in(1)->in(2);
1354 phi1->set_req( i, n1 );
1355 phi2->set_req( i, n2 );
1356 phi1->set_type( phi1->type()->meet_speculative(n1->bottom_type()));
1357 phi2->set_type( phi2->type()->meet_speculative(n2->bottom_type()));
1358 }
1359 // See if these Phis have been made before.
1360 // Register with optimizer
1361 Node *hit1 = _igvn.hash_find_insert(phi1);
1362 if( hit1 ) { // Hit, toss just made Phi
1363 _igvn.remove_dead_node(phi1); // Remove new phi
1364 assert( hit1->is_Phi(), "" );
1365 phi1 = (PhiNode*)hit1; // Use existing phi
1366 } else { // Miss
1367 _igvn.register_new_node_with_optimizer(phi1);
1368 }
1369 Node *hit2 = _igvn.hash_find_insert(phi2);
1370 if( hit2 ) { // Hit, toss just made Phi
1371 _igvn.remove_dead_node(phi2); // Remove new phi
1372 assert( hit2->is_Phi(), "" );
1373 phi2 = (PhiNode*)hit2; // Use existing phi
1374 } else { // Miss
1375 _igvn.register_new_node_with_optimizer(phi2);
1376 }
1377 // Register Phis with loop/block info
1378 set_ctrl(phi1, phi->in(0));
1379 set_ctrl(phi2, phi->in(0));
1380 // Make a new Cmp
1381 Node *cmp = sample_cmp->clone();
1382 cmp->set_req( 1, phi1 );
1383 cmp->set_req( 2, phi2 );
1384 _igvn.register_new_node_with_optimizer(cmp);
1385 set_ctrl(cmp, phi->in(0));
1386
1387 // Make a new Bool
1388 Node *b = sample_bool->clone();
1389 b->set_req(1,cmp);
1390 _igvn.register_new_node_with_optimizer(b);
1391 set_ctrl(b, phi->in(0));
1392
1393 assert( b->is_Bool(), "" );
1394 return (BoolNode*)b;
1395 }
1396
1397 //------------------------------clone_bool-------------------------------------
1398 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1399 // "Nearly" because all Nodes have been cloned from the original in the loop,
1400 // but the fall-in edges to the Cmp are different. Clone bool/Cmp pairs
1401 // through the Phi recursively, and return a Bool.
1402 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1403 uint i;
1404 // Convert this Phi into a Phi merging Bools
1405 for( i = 1; i < phi->req(); i++ ) {
1406 Node *b = phi->in(i);
1407 if( b->is_Phi() ) {
1408 _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1409 } else {
1410 assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1411 }
1412 }
1413
1414 Node *sample_cmp = phi->in(1);
1415
1416 // Make Phis to merge the Cmp's inputs.
1417 PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1418 PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1419 for( uint j = 1; j < phi->req(); j++ ) {
1420 Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1421 Node *n1, *n2;
1422 if( cmp_top->is_Cmp() ) {
1423 n1 = cmp_top->in(1);
1424 n2 = cmp_top->in(2);
1425 } else {
1426 n1 = n2 = cmp_top;
1427 }
1428 phi1->set_req( j, n1 );
1429 phi2->set_req( j, n2 );
1430 phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1431 phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1432 }
1433
1434 // See if these Phis have been made before.
1435 // Register with optimizer
1436 Node *hit1 = _igvn.hash_find_insert(phi1);
1437 if( hit1 ) { // Hit, toss just made Phi
1438 _igvn.remove_dead_node(phi1); // Remove new phi
1439 assert( hit1->is_Phi(), "" );
1440 phi1 = (PhiNode*)hit1; // Use existing phi
1441 } else { // Miss
1442 _igvn.register_new_node_with_optimizer(phi1);
1443 }
1444 Node *hit2 = _igvn.hash_find_insert(phi2);
1445 if( hit2 ) { // Hit, toss just made Phi
1446 _igvn.remove_dead_node(phi2); // Remove new phi
1447 assert( hit2->is_Phi(), "" );
1448 phi2 = (PhiNode*)hit2; // Use existing phi
1449 } else { // Miss
1450 _igvn.register_new_node_with_optimizer(phi2);
1451 }
1452 // Register Phis with loop/block info
1453 set_ctrl(phi1, phi->in(0));
1454 set_ctrl(phi2, phi->in(0));
1455 // Make a new Cmp
1456 Node *cmp = sample_cmp->clone();
1457 cmp->set_req( 1, phi1 );
1458 cmp->set_req( 2, phi2 );
1459 _igvn.register_new_node_with_optimizer(cmp);
1460 set_ctrl(cmp, phi->in(0));
1461
1462 assert( cmp->is_Cmp(), "" );
1463 return (CmpNode*)cmp;
1464 }
1465
1466 //------------------------------sink_use---------------------------------------
1467 // If 'use' was in the loop-exit block, it now needs to be sunk
1468 // below the post-loop merge point.
1469 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1470 if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1471 set_ctrl(use, post_loop);
1472 for (DUIterator j = use->outs(); use->has_out(j); j++)
1473 sink_use(use->out(j), post_loop);
1474 }
1475 }
1476
1477 //------------------------------clone_loop-------------------------------------
1478 //
1479 // C L O N E A L O O P B O D Y
1480 //
1481 // This is the basic building block of the loop optimizations. It clones an
1482 // entire loop body. It makes an old_new loop body mapping; with this mapping
1483 // you can find the new-loop equivalent to an old-loop node. All new-loop
1484 // nodes are exactly equal to their old-loop counterparts, all edges are the
1485 // same. All exits from the old-loop now have a RegionNode that merges the
1486 // equivalent new-loop path. This is true even for the normal "loop-exit"
1487 // condition. All uses of loop-invariant old-loop values now come from (one
1488 // or more) Phis that merge their new-loop equivalents.
1489 //
1490 // This operation leaves the graph in an illegal state: there are two valid
1491 // control edges coming from the loop pre-header to both loop bodies. I'll
1492 // definitely have to hack the graph after running this transform.
1493 //
1494 // From this building block I will further edit edges to perform loop peeling
1495 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1496 //
1497 // Parameter side_by_size_idom:
1498 // When side_by_size_idom is NULL, the dominator tree is constructed for
1499 // the clone loop to dominate the original. Used in construction of
1500 // pre-main-post loop sequence.
1501 // When nonnull, the clone and original are side-by-side, both are
1502 // dominated by the side_by_side_idom node. Used in construction of
1503 // unswitched loops.
1504 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1505 Node* side_by_side_idom) {
1506
1507 if (C->do_vector_loop() && PrintOpto) {
1508 const char* mname = C->method()->name()->as_quoted_ascii();
1509 if (mname != NULL) {
1510 tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
1511 }
1512 }
1513
1514 CloneMap& cm = C->clone_map();
1515 Dict* dict = cm.dict();
1516 if (C->do_vector_loop()) {
1517 cm.set_clone_idx(cm.max_gen()+1);
1518 #ifndef PRODUCT
1519 if (PrintOpto) {
1520 tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
1521 loop->dump_head();
1522 }
1523 #endif
1524 }
1525
1526 // Step 1: Clone the loop body. Make the old->new mapping.
1527 uint i;
1528 for( i = 0; i < loop->_body.size(); i++ ) {
1529 Node *old = loop->_body.at(i);
1530 Node *nnn = old->clone();
1531 old_new.map( old->_idx, nnn );
1532 if (C->do_vector_loop()) {
1533 cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
1534 }
1535 _igvn.register_new_node_with_optimizer(nnn);
1536 }
1537
1538
1539 // Step 2: Fix the edges in the new body. If the old input is outside the
1540 // loop use it. If the old input is INside the loop, use the corresponding
1541 // new node instead.
1542 for( i = 0; i < loop->_body.size(); i++ ) {
1543 Node *old = loop->_body.at(i);
1544 Node *nnn = old_new[old->_idx];
1545 // Fix CFG/Loop controlling the new node
1546 if (has_ctrl(old)) {
1547 set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
1548 } else {
1549 set_loop(nnn, loop->_parent);
1550 if (old->outcnt() > 0) {
1551 set_idom( nnn, old_new[idom(old)->_idx], dd );
1552 }
1553 }
1554 // Correct edges to the new node
1555 for( uint j = 0; j < nnn->req(); j++ ) {
1556 Node *n = nnn->in(j);
1557 if( n ) {
1558 IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
1559 if( loop->is_member( old_in_loop ) )
1560 nnn->set_req(j, old_new[n->_idx]);
1561 }
1562 }
1563 _igvn.hash_find_insert(nnn);
1564 }
1565 Node *newhead = old_new[loop->_head->_idx];
1566 set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1567
1568
1569 // Step 3: Now fix control uses. Loop varying control uses have already
1570 // been fixed up (as part of all input edges in Step 2). Loop invariant
1571 // control uses must be either an IfFalse or an IfTrue. Make a merge
1572 // point to merge the old and new IfFalse/IfTrue nodes; make the use
1573 // refer to this.
1574 ResourceArea *area = Thread::current()->resource_area();
1575 Node_List worklist(area);
1576 uint new_counter = C->unique();
1577 for( i = 0; i < loop->_body.size(); i++ ) {
1578 Node* old = loop->_body.at(i);
1579 if( !old->is_CFG() ) continue;
1580 Node* nnn = old_new[old->_idx];
1581
1582 // Copy uses to a worklist, so I can munge the def-use info
1583 // with impunity.
1584 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1585 worklist.push(old->fast_out(j));
1586
1587 while( worklist.size() ) { // Visit all uses
1588 Node *use = worklist.pop();
1589 if (!has_node(use)) continue; // Ignore dead nodes
1590 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1591 if( !loop->is_member( use_loop ) && use->is_CFG() ) {
1592 // Both OLD and USE are CFG nodes here.
1593 assert( use->is_Proj(), "" );
1594
1595 // Clone the loop exit control projection
1596 Node *newuse = use->clone();
1597 if (C->do_vector_loop()) {
1598 cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
1599 }
1600 newuse->set_req(0,nnn);
1601 _igvn.register_new_node_with_optimizer(newuse);
1602 set_loop(newuse, use_loop);
1603 set_idom(newuse, nnn, dom_depth(nnn) + 1 );
1604
1605 // We need a Region to merge the exit from the peeled body and the
1606 // exit from the old loop body.
1607 RegionNode *r = new RegionNode(3);
1608 // Map the old use to the new merge point
1609 old_new.map( use->_idx, r );
1610 uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
1611 assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
1612
1613 // The original user of 'use' uses 'r' instead.
1614 for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
1615 Node* useuse = use->last_out(l);
1616 _igvn.rehash_node_delayed(useuse);
1617 uint uses_found = 0;
1618 if( useuse->in(0) == use ) {
1619 useuse->set_req(0, r);
1620 uses_found++;
1621 if( useuse->is_CFG() ) {
1622 assert( dom_depth(useuse) > dd_r, "" );
1623 set_idom(useuse, r, dom_depth(useuse));
1624 }
1625 }
1626 for( uint k = 1; k < useuse->req(); k++ ) {
1627 if( useuse->in(k) == use ) {
1628 useuse->set_req(k, r);
1629 uses_found++;
1630 }
1631 }
1632 l -= uses_found; // we deleted 1 or more copies of this edge
1633 }
1634
1635 // Now finish up 'r'
1636 r->set_req( 1, newuse );
1637 r->set_req( 2, use );
1638 _igvn.register_new_node_with_optimizer(r);
1639 set_loop(r, use_loop);
1640 set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
1641 } // End of if a loop-exit test
1642 }
1643 }
1644
1645 // Step 4: If loop-invariant use is not control, it must be dominated by a
1646 // loop exit IfFalse/IfTrue. Find "proper" loop exit. Make a Region
1647 // there if needed. Make a Phi there merging old and new used values.
1648 Node_List *split_if_set = NULL;
1649 Node_List *split_bool_set = NULL;
1650 Node_List *split_cex_set = NULL;
1651 for( i = 0; i < loop->_body.size(); i++ ) {
1652 Node* old = loop->_body.at(i);
1653 Node* nnn = old_new[old->_idx];
1654 // Copy uses to a worklist, so I can munge the def-use info
1655 // with impunity.
1656 for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1657 worklist.push(old->fast_out(j));
1658
1659 while( worklist.size() ) {
1660 Node *use = worklist.pop();
1661 if (!has_node(use)) continue; // Ignore dead nodes
1662 if (use->in(0) == C->top()) continue;
1663 IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1664 // Check for data-use outside of loop - at least one of OLD or USE
1665 // must not be a CFG node.
1666 if( !loop->is_member( use_loop ) && (!old->is_CFG() || !use->is_CFG())) {
1667
1668 // If the Data use is an IF, that means we have an IF outside of the
1669 // loop that is switching on a condition that is set inside of the
1670 // loop. Happens if people set a loop-exit flag; then test the flag
1671 // in the loop to break the loop, then test is again outside of the
1672 // loop to determine which way the loop exited.
1673 // Loop predicate If node connects to Bool node through Opaque1 node.
1674 if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use)) {
1675 // Since this code is highly unlikely, we lazily build the worklist
1676 // of such Nodes to go split.
1677 if( !split_if_set )
1678 split_if_set = new Node_List(area);
1679 split_if_set->push(use);
1680 }
1681 if( use->is_Bool() ) {
1682 if( !split_bool_set )
1683 split_bool_set = new Node_List(area);
1684 split_bool_set->push(use);
1685 }
1686 if( use->Opcode() == Op_CreateEx ) {
1687 if( !split_cex_set )
1688 split_cex_set = new Node_List(area);
1689 split_cex_set->push(use);
1690 }
1691
1692
1693 // Get "block" use is in
1694 uint idx = 0;
1695 while( use->in(idx) != old ) idx++;
1696 Node *prev = use->is_CFG() ? use : get_ctrl(use);
1697 assert( !loop->is_member( get_loop( prev ) ), "" );
1698 Node *cfg = prev->_idx >= new_counter
1699 ? prev->in(2)
1700 : idom(prev);
1701 if( use->is_Phi() ) // Phi use is in prior block
1702 cfg = prev->in(idx); // NOT in block of Phi itself
1703 if (cfg->is_top()) { // Use is dead?
1704 _igvn.replace_input_of(use, idx, C->top());
1705 continue;
1706 }
1707
1708 while( !loop->is_member( get_loop( cfg ) ) ) {
1709 prev = cfg;
1710 cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1711 }
1712 // If the use occurs after merging several exits from the loop, then
1713 // old value must have dominated all those exits. Since the same old
1714 // value was used on all those exits we did not need a Phi at this
1715 // merge point. NOW we do need a Phi here. Each loop exit value
1716 // is now merged with the peeled body exit; each exit gets its own
1717 // private Phi and those Phis need to be merged here.
1718 Node *phi;
1719 if( prev->is_Region() ) {
1720 if( idx == 0 ) { // Updating control edge?
1721 phi = prev; // Just use existing control
1722 } else { // Else need a new Phi
1723 phi = PhiNode::make( prev, old );
1724 // Now recursively fix up the new uses of old!
1725 for( uint i = 1; i < prev->req(); i++ ) {
1726 worklist.push(phi); // Onto worklist once for each 'old' input
1727 }
1728 }
1729 } else {
1730 // Get new RegionNode merging old and new loop exits
1731 prev = old_new[prev->_idx];
1732 assert( prev, "just made this in step 7" );
1733 if( idx == 0 ) { // Updating control edge?
1734 phi = prev; // Just use existing control
1735 } else { // Else need a new Phi
1736 // Make a new Phi merging data values properly
1737 phi = PhiNode::make( prev, old );
1738 phi->set_req( 1, nnn );
1739 }
1740 }
1741 // If inserting a new Phi, check for prior hits
1742 if( idx != 0 ) {
1743 Node *hit = _igvn.hash_find_insert(phi);
1744 if( hit == NULL ) {
1745 _igvn.register_new_node_with_optimizer(phi); // Register new phi
1746 } else { // or
1747 // Remove the new phi from the graph and use the hit
1748 _igvn.remove_dead_node(phi);
1749 phi = hit; // Use existing phi
1750 }
1751 set_ctrl(phi, prev);
1752 }
1753 // Make 'use' use the Phi instead of the old loop body exit value
1754 _igvn.replace_input_of(use, idx, phi);
1755 if( use->_idx >= new_counter ) { // If updating new phis
1756 // Not needed for correctness, but prevents a weak assert
1757 // in AddPNode from tripping (when we end up with different
1758 // base & derived Phis that will become the same after
1759 // IGVN does CSE).
1760 Node *hit = _igvn.hash_find_insert(use);
1761 if( hit ) // Go ahead and re-hash for hits.
1762 _igvn.replace_node( use, hit );
1763 }
1764
1765 // If 'use' was in the loop-exit block, it now needs to be sunk
1766 // below the post-loop merge point.
1767 sink_use( use, prev );
1768 }
1769 }
1770 }
1771
1772 // Check for IFs that need splitting/cloning. Happens if an IF outside of
1773 // the loop uses a condition set in the loop. The original IF probably
1774 // takes control from one or more OLD Regions (which in turn get from NEW
1775 // Regions). In any case, there will be a set of Phis for each merge point
1776 // from the IF up to where the original BOOL def exists the loop.
1777 if( split_if_set ) {
1778 while( split_if_set->size() ) {
1779 Node *iff = split_if_set->pop();
1780 if( iff->in(1)->is_Phi() ) {
1781 BoolNode *b = clone_iff( iff->in(1)->as_Phi(), loop );
1782 _igvn.replace_input_of(iff, 1, b);
1783 }
1784 }
1785 }
1786 if( split_bool_set ) {
1787 while( split_bool_set->size() ) {
1788 Node *b = split_bool_set->pop();
1789 Node *phi = b->in(1);
1790 assert( phi->is_Phi(), "" );
1791 CmpNode *cmp = clone_bool( (PhiNode*)phi, loop );
1792 _igvn.replace_input_of(b, 1, cmp);
1793 }
1794 }
1795 if( split_cex_set ) {
1796 while( split_cex_set->size() ) {
1797 Node *b = split_cex_set->pop();
1798 assert( b->in(0)->is_Region(), "" );
1799 assert( b->in(1)->is_Phi(), "" );
1800 assert( b->in(0)->in(0) == b->in(1)->in(0), "" );
1801 split_up( b, b->in(0), NULL );
1802 }
1803 }
1804
1805 }
1806
1807
1808 //---------------------- stride_of_possible_iv -------------------------------------
1809 // Looks for an iff/bool/comp with one operand of the compare
1810 // being a cycle involving an add and a phi,
1811 // with an optional truncation (left-shift followed by a right-shift)
1812 // of the add. Returns zero if not an iv.
1813 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
1814 Node* trunc1 = NULL;
1815 Node* trunc2 = NULL;
1816 const TypeInt* ttype = NULL;
1817 if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
1818 return 0;
1819 }
1820 BoolNode* bl = iff->in(1)->as_Bool();
1821 Node* cmp = bl->in(1);
1822 if (!cmp || cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU) {
1823 return 0;
1824 }
1825 // Must have an invariant operand
1826 if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
1827 return 0;
1828 }
1829 Node* add2 = NULL;
1830 Node* cmp1 = cmp->in(1);
1831 if (cmp1->is_Phi()) {
1832 // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
1833 Node* phi = cmp1;
1834 for (uint i = 1; i < phi->req(); i++) {
1835 Node* in = phi->in(i);
1836 Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
1837 &trunc1, &trunc2, &ttype);
1838 if (add && add->in(1) == phi) {
1839 add2 = add->in(2);
1840 break;
1841 }
1842 }
1843 } else {
1844 // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
1845 Node* addtrunc = cmp1;
1846 Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
1847 &trunc1, &trunc2, &ttype);
1848 if (add && add->in(1)->is_Phi()) {
1849 Node* phi = add->in(1);
1850 for (uint i = 1; i < phi->req(); i++) {
1851 if (phi->in(i) == addtrunc) {
1852 add2 = add->in(2);
1853 break;
1854 }
1855 }
1856 }
1857 }
1858 if (add2 != NULL) {
1859 const TypeInt* add2t = _igvn.type(add2)->is_int();
1860 if (add2t->is_con()) {
1861 return add2t->get_con();
1862 }
1863 }
1864 return 0;
1865 }
1866
1867
1868 //---------------------- stay_in_loop -------------------------------------
1869 // Return the (unique) control output node that's in the loop (if it exists.)
1870 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
1871 Node* unique = NULL;
1872 if (!n) return NULL;
1873 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1874 Node* use = n->fast_out(i);
1875 if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
1876 if (unique != NULL) {
1877 return NULL;
1878 }
1879 unique = use;
1880 }
1881 }
1882 return unique;
1883 }
1884
1885 //------------------------------ register_node -------------------------------------
1886 // Utility to register node "n" with PhaseIdealLoop
1887 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
1888 _igvn.register_new_node_with_optimizer(n);
1889 loop->_body.push(n);
1890 if (n->is_CFG()) {
1891 set_loop(n, loop);
1892 set_idom(n, pred, ddepth);
1893 } else {
1894 set_ctrl(n, pred);
1895 }
1896 }
1897
1898 //------------------------------ proj_clone -------------------------------------
1899 // Utility to create an if-projection
1900 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
1901 ProjNode* c = p->clone()->as_Proj();
1902 c->set_req(0, iff);
1903 return c;
1904 }
1905
1906 //------------------------------ short_circuit_if -------------------------------------
1907 // Force the iff control output to be the live_proj
1908 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
1909 guarantee(live_proj != NULL, "null projection");
1910 int proj_con = live_proj->_con;
1911 assert(proj_con == 0 || proj_con == 1, "false or true projection");
1912 Node *con = _igvn.intcon(proj_con);
1913 set_ctrl(con, C->root());
1914 if (iff) {
1915 iff->set_req(1, con);
1916 }
1917 return con;
1918 }
1919
1920 //------------------------------ insert_if_before_proj -------------------------------------
1921 // Insert a new if before an if projection (* - new node)
1922 //
1923 // before
1924 // if(test)
1925 // / \
1926 // v v
1927 // other-proj proj (arg)
1928 //
1929 // after
1930 // if(test)
1931 // / \
1932 // / v
1933 // | * proj-clone
1934 // v |
1935 // other-proj v
1936 // * new_if(relop(cmp[IU](left,right)))
1937 // / \
1938 // v v
1939 // * new-proj proj
1940 // (returned)
1941 //
1942 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
1943 IfNode* iff = proj->in(0)->as_If();
1944 IdealLoopTree *loop = get_loop(proj);
1945 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
1946 int ddepth = dom_depth(proj);
1947
1948 _igvn.rehash_node_delayed(iff);
1949 _igvn.rehash_node_delayed(proj);
1950
1951 proj->set_req(0, NULL); // temporary disconnect
1952 ProjNode* proj2 = proj_clone(proj, iff);
1953 register_node(proj2, loop, iff, ddepth);
1954
1955 Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
1956 register_node(cmp, loop, proj2, ddepth);
1957
1958 BoolNode* bol = new BoolNode(cmp, relop);
1959 register_node(bol, loop, proj2, ddepth);
1960
1961 int opcode = iff->Opcode();
1962 assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
1963 IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
1964 new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
1965 register_node(new_if, loop, proj2, ddepth);
1966
1967 proj->set_req(0, new_if); // reattach
1968 set_idom(proj, new_if, ddepth);
1969
1970 ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
1971 guarantee(new_exit != NULL, "null exit node");
1972 register_node(new_exit, get_loop(other_proj), new_if, ddepth);
1973
1974 return new_exit;
1975 }
1976
1977 //------------------------------ insert_region_before_proj -------------------------------------
1978 // Insert a region before an if projection (* - new node)
1979 //
1980 // before
1981 // if(test)
1982 // / |
1983 // v |
1984 // proj v
1985 // other-proj
1986 //
1987 // after
1988 // if(test)
1989 // / |
1990 // v |
1991 // * proj-clone v
1992 // | other-proj
1993 // v
1994 // * new-region
1995 // |
1996 // v
1997 // * dum_if
1998 // / \
1999 // v \
2000 // * dum-proj v
2001 // proj
2002 //
2003 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2004 IfNode* iff = proj->in(0)->as_If();
2005 IdealLoopTree *loop = get_loop(proj);
2006 ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2007 int ddepth = dom_depth(proj);
2008
2009 _igvn.rehash_node_delayed(iff);
2010 _igvn.rehash_node_delayed(proj);
2011
2012 proj->set_req(0, NULL); // temporary disconnect
2013 ProjNode* proj2 = proj_clone(proj, iff);
2014 register_node(proj2, loop, iff, ddepth);
2015
2016 RegionNode* reg = new RegionNode(2);
2017 reg->set_req(1, proj2);
2018 register_node(reg, loop, iff, ddepth);
2019
2020 IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2021 register_node(dum_if, loop, reg, ddepth);
2022
2023 proj->set_req(0, dum_if); // reattach
2024 set_idom(proj, dum_if, ddepth);
2025
2026 ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2027 register_node(dum_proj, loop, dum_if, ddepth);
2028
2029 return reg;
2030 }
2031
2032 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2033 // Clone a signed compare loop exit from an unsigned compare and
2034 // insert it before the unsigned cmp on the stay-in-loop path.
2035 // All new nodes inserted in the dominator tree between the original
2036 // if and it's projections. The original if test is replaced with
2037 // a constant to force the stay-in-loop path.
2038 //
2039 // This is done to make sure that the original if and it's projections
2040 // still dominate the same set of control nodes, that the ctrl() relation
2041 // from data nodes to them is preserved, and that their loop nesting is
2042 // preserved.
2043 //
2044 // before
2045 // if(i <u limit) unsigned compare loop exit
2046 // / |
2047 // v v
2048 // exit-proj stay-in-loop-proj
2049 //
2050 // after
2051 // if(stay-in-loop-const) original if
2052 // / |
2053 // / v
2054 // / if(i < limit) new signed test
2055 // / / |
2056 // / / v
2057 // / / if(i <u limit) new cloned unsigned test
2058 // / / / |
2059 // v v v |
2060 // region |
2061 // | |
2062 // dum-if |
2063 // / | |
2064 // ether | |
2065 // v v
2066 // exit-proj stay-in-loop-proj
2067 //
2068 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2069 const bool Signed = true;
2070 const bool Unsigned = false;
2071
2072 BoolNode* bol = if_cmpu->in(1)->as_Bool();
2073 if (bol->_test._test != BoolTest::lt) return NULL;
2074 CmpNode* cmpu = bol->in(1)->as_Cmp();
2075 if (cmpu->Opcode() != Op_CmpU) return NULL;
2076 int stride = stride_of_possible_iv(if_cmpu);
2077 if (stride == 0) return NULL;
2078
2079 Node* lp_proj = stay_in_loop(if_cmpu, loop);
2080 guarantee(lp_proj != NULL, "null loop node");
2081
2082 ProjNode* lp_continue = lp_proj->as_Proj();
2083 ProjNode* lp_exit = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2084
2085 Node* limit = NULL;
2086 if (stride > 0) {
2087 limit = cmpu->in(2);
2088 } else {
2089 limit = _igvn.makecon(TypeInt::ZERO);
2090 set_ctrl(limit, C->root());
2091 }
2092 // Create a new region on the exit path
2093 RegionNode* reg = insert_region_before_proj(lp_exit);
2094 guarantee(reg != NULL, "null region node");
2095
2096 // Clone the if-cmpu-true-false using a signed compare
2097 BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2098 ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2099 reg->add_req(cmpi_exit);
2100
2101 // Clone the if-cmpu-true-false
2102 BoolTest::mask rel_u = bol->_test._test;
2103 ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2104 reg->add_req(cmpu_exit);
2105
2106 // Force original if to stay in loop.
2107 short_circuit_if(if_cmpu, lp_continue);
2108
2109 return cmpi_exit->in(0)->as_If();
2110 }
2111
2112 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2113 // Remove a previously inserted signed compare loop exit.
2114 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2115 Node* lp_proj = stay_in_loop(if_cmp, loop);
2116 assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2117 stay_in_loop(lp_proj, loop)->is_If() &&
2118 stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2119 Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2120 set_ctrl(con, C->root());
2121 if_cmp->set_req(1, con);
2122 }
2123
2124 //------------------------------ scheduled_nodelist -------------------------------------
2125 // Create a post order schedule of nodes that are in the
2126 // "member" set. The list is returned in "sched".
2127 // The first node in "sched" is the loop head, followed by
2128 // nodes which have no inputs in the "member" set, and then
2129 // followed by the nodes that have an immediate input dependence
2130 // on a node in "sched".
2131 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2132
2133 assert(member.test(loop->_head->_idx), "loop head must be in member set");
2134 Arena *a = Thread::current()->resource_area();
2135 VectorSet visited(a);
2136 Node_Stack nstack(a, loop->_body.size());
2137
2138 Node* n = loop->_head; // top of stack is cached in "n"
2139 uint idx = 0;
2140 visited.set(n->_idx);
2141
2142 // Initially push all with no inputs from within member set
2143 for(uint i = 0; i < loop->_body.size(); i++ ) {
2144 Node *elt = loop->_body.at(i);
2145 if (member.test(elt->_idx)) {
2146 bool found = false;
2147 for (uint j = 0; j < elt->req(); j++) {
2148 Node* def = elt->in(j);
2149 if (def && member.test(def->_idx) && def != elt) {
2150 found = true;
2151 break;
2152 }
2153 }
2154 if (!found && elt != loop->_head) {
2155 nstack.push(n, idx);
2156 n = elt;
2157 assert(!visited.test(n->_idx), "not seen yet");
2158 visited.set(n->_idx);
2159 }
2160 }
2161 }
2162
2163 // traverse out's that are in the member set
2164 while (true) {
2165 if (idx < n->outcnt()) {
2166 Node* use = n->raw_out(idx);
2167 idx++;
2168 if (!visited.test_set(use->_idx)) {
2169 if (member.test(use->_idx)) {
2170 nstack.push(n, idx);
2171 n = use;
2172 idx = 0;
2173 }
2174 }
2175 } else {
2176 // All outputs processed
2177 sched.push(n);
2178 if (nstack.is_empty()) break;
2179 n = nstack.node();
2180 idx = nstack.index();
2181 nstack.pop();
2182 }
2183 }
2184 }
2185
2186
2187 //------------------------------ has_use_in_set -------------------------------------
2188 // Has a use in the vector set
2189 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2190 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2191 Node* use = n->fast_out(j);
2192 if (vset.test(use->_idx)) {
2193 return true;
2194 }
2195 }
2196 return false;
2197 }
2198
2199
2200 //------------------------------ has_use_internal_to_set -------------------------------------
2201 // Has use internal to the vector set (ie. not in a phi at the loop head)
2202 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2203 Node* head = loop->_head;
2204 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2205 Node* use = n->fast_out(j);
2206 if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2207 return true;
2208 }
2209 }
2210 return false;
2211 }
2212
2213
2214 //------------------------------ clone_for_use_outside_loop -------------------------------------
2215 // clone "n" for uses that are outside of loop
2216 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2217 int cloned = 0;
2218 assert(worklist.size() == 0, "should be empty");
2219 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2220 Node* use = n->fast_out(j);
2221 if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2222 worklist.push(use);
2223 }
2224 }
2225 while( worklist.size() ) {
2226 Node *use = worklist.pop();
2227 if (!has_node(use) || use->in(0) == C->top()) continue;
2228 uint j;
2229 for (j = 0; j < use->req(); j++) {
2230 if (use->in(j) == n) break;
2231 }
2232 assert(j < use->req(), "must be there");
2233
2234 // clone "n" and insert it between the inputs of "n" and the use outside the loop
2235 Node* n_clone = n->clone();
2236 _igvn.replace_input_of(use, j, n_clone);
2237 cloned++;
2238 Node* use_c;
2239 if (!use->is_Phi()) {
2240 use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2241 } else {
2242 // Use in a phi is considered a use in the associated predecessor block
2243 use_c = use->in(0)->in(j);
2244 }
2245 set_ctrl(n_clone, use_c);
2246 assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2247 get_loop(use_c)->_body.push(n_clone);
2248 _igvn.register_new_node_with_optimizer(n_clone);
2249 #if !defined(PRODUCT)
2250 if (TracePartialPeeling) {
2251 tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2252 }
2253 #endif
2254 }
2255 return cloned;
2256 }
2257
2258
2259 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2260 // clone "n" for special uses that are in the not_peeled region.
2261 // If these def-uses occur in separate blocks, the code generator
2262 // marks the method as not compilable. For example, if a "BoolNode"
2263 // is in a different basic block than the "IfNode" that uses it, then
2264 // the compilation is aborted in the code generator.
2265 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2266 VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2267 if (n->is_Phi() || n->is_Load()) {
2268 return;
2269 }
2270 assert(worklist.size() == 0, "should be empty");
2271 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2272 Node* use = n->fast_out(j);
2273 if ( not_peel.test(use->_idx) &&
2274 (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2275 use->in(1) == n) {
2276 worklist.push(use);
2277 }
2278 }
2279 if (worklist.size() > 0) {
2280 // clone "n" and insert it between inputs of "n" and the use
2281 Node* n_clone = n->clone();
2282 loop->_body.push(n_clone);
2283 _igvn.register_new_node_with_optimizer(n_clone);
2284 set_ctrl(n_clone, get_ctrl(n));
2285 sink_list.push(n_clone);
2286 not_peel <<= n_clone->_idx; // add n_clone to not_peel set.
2287 #if !defined(PRODUCT)
2288 if (TracePartialPeeling) {
2289 tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2290 }
2291 #endif
2292 while( worklist.size() ) {
2293 Node *use = worklist.pop();
2294 _igvn.rehash_node_delayed(use);
2295 for (uint j = 1; j < use->req(); j++) {
2296 if (use->in(j) == n) {
2297 use->set_req(j, n_clone);
2298 }
2299 }
2300 }
2301 }
2302 }
2303
2304
2305 //------------------------------ insert_phi_for_loop -------------------------------------
2306 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2307 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2308 Node *phi = PhiNode::make(lp, back_edge_val);
2309 phi->set_req(LoopNode::EntryControl, lp_entry_val);
2310 // Use existing phi if it already exists
2311 Node *hit = _igvn.hash_find_insert(phi);
2312 if( hit == NULL ) {
2313 _igvn.register_new_node_with_optimizer(phi);
2314 set_ctrl(phi, lp);
2315 } else {
2316 // Remove the new phi from the graph and use the hit
2317 _igvn.remove_dead_node(phi);
2318 phi = hit;
2319 }
2320 _igvn.replace_input_of(use, idx, phi);
2321 }
2322
2323 #ifdef ASSERT
2324 //------------------------------ is_valid_loop_partition -------------------------------------
2325 // Validate the loop partition sets: peel and not_peel
2326 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2327 VectorSet& not_peel ) {
2328 uint i;
2329 // Check that peel_list entries are in the peel set
2330 for (i = 0; i < peel_list.size(); i++) {
2331 if (!peel.test(peel_list.at(i)->_idx)) {
2332 return false;
2333 }
2334 }
2335 // Check at loop members are in one of peel set or not_peel set
2336 for (i = 0; i < loop->_body.size(); i++ ) {
2337 Node *def = loop->_body.at(i);
2338 uint di = def->_idx;
2339 // Check that peel set elements are in peel_list
2340 if (peel.test(di)) {
2341 if (not_peel.test(di)) {
2342 return false;
2343 }
2344 // Must be in peel_list also
2345 bool found = false;
2346 for (uint j = 0; j < peel_list.size(); j++) {
2347 if (peel_list.at(j)->_idx == di) {
2348 found = true;
2349 break;
2350 }
2351 }
2352 if (!found) {
2353 return false;
2354 }
2355 } else if (not_peel.test(di)) {
2356 if (peel.test(di)) {
2357 return false;
2358 }
2359 } else {
2360 return false;
2361 }
2362 }
2363 return true;
2364 }
2365
2366 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2367 // Ensure a use outside of loop is of the right form
2368 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2369 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2370 return (use->is_Phi() &&
2371 use_c->is_Region() && use_c->req() == 3 &&
2372 (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2373 use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2374 use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2375 loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2376 }
2377
2378 //------------------------------ is_valid_clone_loop_form -------------------------------------
2379 // Ensure that all uses outside of loop are of the right form
2380 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2381 uint orig_exit_idx, uint clone_exit_idx) {
2382 uint len = peel_list.size();
2383 for (uint i = 0; i < len; i++) {
2384 Node *def = peel_list.at(i);
2385
2386 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2387 Node *use = def->fast_out(j);
2388 Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2389 if (!loop->is_member(get_loop(use_c))) {
2390 // use is not in the loop, check for correct structure
2391 if (use->in(0) == def) {
2392 // Okay
2393 } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2394 return false;
2395 }
2396 }
2397 }
2398 }
2399 return true;
2400 }
2401 #endif
2402
2403 //------------------------------ partial_peel -------------------------------------
2404 // Partially peel (aka loop rotation) the top portion of a loop (called
2405 // the peel section below) by cloning it and placing one copy just before
2406 // the new loop head and the other copy at the bottom of the new loop.
2407 //
2408 // before after where it came from
2409 //
2410 // stmt1 stmt1
2411 // loop: stmt2 clone
2412 // stmt2 if condA goto exitA clone
2413 // if condA goto exitA new_loop: new
2414 // stmt3 stmt3 clone
2415 // if !condB goto loop if condB goto exitB clone
2416 // exitB: stmt2 orig
2417 // stmt4 if !condA goto new_loop orig
2418 // exitA: goto exitA
2419 // exitB:
2420 // stmt4
2421 // exitA:
2422 //
2423 // Step 1: find the cut point: an exit test on probable
2424 // induction variable.
2425 // Step 2: schedule (with cloning) operations in the peel
2426 // section that can be executed after the cut into
2427 // the section that is not peeled. This may need
2428 // to clone operations into exit blocks. For
2429 // instance, a reference to A[i] in the not-peel
2430 // section and a reference to B[i] in an exit block
2431 // may cause a left-shift of i by 2 to be placed
2432 // in the peel block. This step will clone the left
2433 // shift into the exit block and sink the left shift
2434 // from the peel to the not-peel section.
2435 // Step 3: clone the loop, retarget the control, and insert
2436 // phis for values that are live across the new loop
2437 // head. This is very dependent on the graph structure
2438 // from clone_loop. It creates region nodes for
2439 // exit control and associated phi nodes for values
2440 // flow out of the loop through that exit. The region
2441 // node is dominated by the clone's control projection.
2442 // So the clone's peel section is placed before the
2443 // new loop head, and the clone's not-peel section is
2444 // forms the top part of the new loop. The original
2445 // peel section forms the tail of the new loop.
2446 // Step 4: update the dominator tree and recompute the
2447 // dominator depth.
2448 //
2449 // orig
2450 //
2451 // stmt1
2452 // |
2453 // v
2454 // loop predicate
2455 // |
2456 // v
2457 // loop<----+
2458 // | |
2459 // stmt2 |
2460 // | |
2461 // v |
2462 // ifA |
2463 // / | |
2464 // v v |
2465 // false true ^ <-- last_peel
2466 // / | |
2467 // / ===|==cut |
2468 // / stmt3 | <-- first_not_peel
2469 // / | |
2470 // | v |
2471 // v ifB |
2472 // exitA: / \ |
2473 // / \ |
2474 // v v |
2475 // false true |
2476 // / \ |
2477 // / ----+
2478 // |
2479 // v
2480 // exitB:
2481 // stmt4
2482 //
2483 //
2484 // after clone loop
2485 //
2486 // stmt1
2487 // |
2488 // v
2489 // loop predicate
2490 // / \
2491 // clone / \ orig
2492 // / \
2493 // / \
2494 // v v
2495 // +---->loop loop<----+
2496 // | | | |
2497 // | stmt2 stmt2 |
2498 // | | | |
2499 // | v v |
2500 // | ifA ifA |
2501 // | | \ / | |
2502 // | v v v v |
2503 // ^ true false false true ^ <-- last_peel
2504 // | | ^ \ / | |
2505 // | cut==|== \ \ / ===|==cut |
2506 // | stmt3 \ \ / stmt3 | <-- first_not_peel
2507 // | | dom | | | |
2508 // | v \ 1v v2 v |
2509 // | ifB regionA ifB |
2510 // | / \ | / \ |
2511 // | / \ v / \ |
2512 // | v v exitA: v v |
2513 // | true false false true |
2514 // | / ^ \ / \ |
2515 // +---- \ \ / ----+
2516 // dom \ /
2517 // \ 1v v2
2518 // regionB
2519 // |
2520 // v
2521 // exitB:
2522 // stmt4
2523 //
2524 //
2525 // after partial peel
2526 //
2527 // stmt1
2528 // |
2529 // v
2530 // loop predicate
2531 // /
2532 // clone / orig
2533 // / TOP
2534 // / \
2535 // v v
2536 // TOP->loop loop----+
2537 // | | |
2538 // stmt2 stmt2 |
2539 // | | |
2540 // v v |
2541 // ifA ifA |
2542 // | \ / | |
2543 // v v v v |
2544 // true false false true | <-- last_peel
2545 // | ^ \ / +------|---+
2546 // +->newloop \ \ / === ==cut | |
2547 // | stmt3 \ \ / TOP | |
2548 // | | dom | | stmt3 | | <-- first_not_peel
2549 // | v \ 1v v2 v | |
2550 // | ifB regionA ifB ^ v
2551 // | / \ | / \ | |
2552 // | / \ v / \ | |
2553 // | v v exitA: v v | |
2554 // | true false false true | |
2555 // | / ^ \ / \ | |
2556 // | | \ \ / v | |
2557 // | | dom \ / TOP | |
2558 // | | \ 1v v2 | |
2559 // ^ v regionB | |
2560 // | | | | |
2561 // | | v ^ v
2562 // | | exitB: | |
2563 // | | stmt4 | |
2564 // | +------------>-----------------+ |
2565 // | |
2566 // +-----------------<---------------------+
2567 //
2568 //
2569 // final graph
2570 //
2571 // stmt1
2572 // |
2573 // v
2574 // loop predicate
2575 // |
2576 // v
2577 // stmt2 clone
2578 // |
2579 // v
2580 // ........> ifA clone
2581 // : / |
2582 // dom / |
2583 // : v v
2584 // : false true
2585 // : | |
2586 // : | v
2587 // : | newloop<-----+
2588 // : | | |
2589 // : | stmt3 clone |
2590 // : | | |
2591 // : | v |
2592 // : | ifB |
2593 // : | / \ |
2594 // : | v v |
2595 // : | false true |
2596 // : | | | |
2597 // : | v stmt2 |
2598 // : | exitB: | |
2599 // : | stmt4 v |
2600 // : | ifA orig |
2601 // : | / \ |
2602 // : | / \ |
2603 // : | v v |
2604 // : | false true |
2605 // : | / \ |
2606 // : v v -----+
2607 // RegionA
2608 // |
2609 // v
2610 // exitA
2611 //
2612 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
2613
2614 assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
2615 if (!loop->_head->is_Loop()) {
2616 return false; }
2617
2618 LoopNode *head = loop->_head->as_Loop();
2619
2620 if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
2621 return false;
2622 }
2623
2624 // Check for complex exit control
2625 for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
2626 Node *n = loop->_body.at(ii);
2627 int opc = n->Opcode();
2628 if (n->is_Call() ||
2629 opc == Op_Catch ||
2630 opc == Op_CatchProj ||
2631 opc == Op_Jump ||
2632 opc == Op_JumpProj) {
2633 #if !defined(PRODUCT)
2634 if (TracePartialPeeling) {
2635 tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
2636 }
2637 #endif
2638 return false;
2639 }
2640 }
2641
2642 int dd = dom_depth(head);
2643
2644 // Step 1: find cut point
2645
2646 // Walk up dominators to loop head looking for first loop exit
2647 // which is executed on every path thru loop.
2648 IfNode *peel_if = NULL;
2649 IfNode *peel_if_cmpu = NULL;
2650
2651 Node *iff = loop->tail();
2652 while( iff != head ) {
2653 if( iff->is_If() ) {
2654 Node *ctrl = get_ctrl(iff->in(1));
2655 if (ctrl->is_top()) return false; // Dead test on live IF.
2656 // If loop-varying exit-test, check for induction variable
2657 if( loop->is_member(get_loop(ctrl)) &&
2658 loop->is_loop_exit(iff) &&
2659 is_possible_iv_test(iff)) {
2660 Node* cmp = iff->in(1)->in(1);
2661 if (cmp->Opcode() == Op_CmpI) {
2662 peel_if = iff->as_If();
2663 } else {
2664 assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
2665 peel_if_cmpu = iff->as_If();
2666 }
2667 }
2668 }
2669 iff = idom(iff);
2670 }
2671 // Prefer signed compare over unsigned compare.
2672 IfNode* new_peel_if = NULL;
2673 if (peel_if == NULL) {
2674 if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
2675 return false; // No peel point found
2676 }
2677 new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
2678 if (new_peel_if == NULL) {
2679 return false; // No peel point found
2680 }
2681 peel_if = new_peel_if;
2682 }
2683 Node* last_peel = stay_in_loop(peel_if, loop);
2684 Node* first_not_peeled = stay_in_loop(last_peel, loop);
2685 if (first_not_peeled == NULL || first_not_peeled == head) {
2686 return false;
2687 }
2688
2689 #if !defined(PRODUCT)
2690 if (TraceLoopOpts) {
2691 tty->print("PartialPeel ");
2692 loop->dump_head();
2693 }
2694
2695 if (TracePartialPeeling) {
2696 tty->print_cr("before partial peel one iteration");
2697 Node_List wl;
2698 Node* t = head->in(2);
2699 while (true) {
2700 wl.push(t);
2701 if (t == head) break;
2702 t = idom(t);
2703 }
2704 while (wl.size() > 0) {
2705 Node* tt = wl.pop();
2706 tt->dump();
2707 if (tt == last_peel) tty->print_cr("-- cut --");
2708 }
2709 }
2710 #endif
2711 ResourceArea *area = Thread::current()->resource_area();
2712 VectorSet peel(area);
2713 VectorSet not_peel(area);
2714 Node_List peel_list(area);
2715 Node_List worklist(area);
2716 Node_List sink_list(area);
2717
2718 // Set of cfg nodes to peel are those that are executable from
2719 // the head through last_peel.
2720 assert(worklist.size() == 0, "should be empty");
2721 worklist.push(head);
2722 peel.set(head->_idx);
2723 while (worklist.size() > 0) {
2724 Node *n = worklist.pop();
2725 if (n != last_peel) {
2726 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2727 Node* use = n->fast_out(j);
2728 if (use->is_CFG() &&
2729 loop->is_member(get_loop(use)) &&
2730 !peel.test_set(use->_idx)) {
2731 worklist.push(use);
2732 }
2733 }
2734 }
2735 }
2736
2737 // Set of non-cfg nodes to peel are those that are control
2738 // dependent on the cfg nodes.
2739 uint i;
2740 for(i = 0; i < loop->_body.size(); i++ ) {
2741 Node *n = loop->_body.at(i);
2742 Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
2743 if (peel.test(n_c->_idx)) {
2744 peel.set(n->_idx);
2745 } else {
2746 not_peel.set(n->_idx);
2747 }
2748 }
2749
2750 // Step 2: move operations from the peeled section down into the
2751 // not-peeled section
2752
2753 // Get a post order schedule of nodes in the peel region
2754 // Result in right-most operand.
2755 scheduled_nodelist(loop, peel, peel_list );
2756
2757 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2758
2759 // For future check for too many new phis
2760 uint old_phi_cnt = 0;
2761 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2762 Node* use = head->fast_out(j);
2763 if (use->is_Phi()) old_phi_cnt++;
2764 }
2765
2766 #if !defined(PRODUCT)
2767 if (TracePartialPeeling) {
2768 tty->print_cr("\npeeled list");
2769 }
2770 #endif
2771
2772 // Evacuate nodes in peel region into the not_peeled region if possible
2773 uint new_phi_cnt = 0;
2774 uint cloned_for_outside_use = 0;
2775 for (i = 0; i < peel_list.size();) {
2776 Node* n = peel_list.at(i);
2777 #if !defined(PRODUCT)
2778 if (TracePartialPeeling) n->dump();
2779 #endif
2780 bool incr = true;
2781 if ( !n->is_CFG() ) {
2782
2783 if ( has_use_in_set(n, not_peel) ) {
2784
2785 // If not used internal to the peeled region,
2786 // move "n" from peeled to not_peeled region.
2787
2788 if ( !has_use_internal_to_set(n, peel, loop) ) {
2789
2790 // if not pinned and not a load (which maybe anti-dependent on a store)
2791 // and not a CMove (Matcher expects only bool->cmove).
2792 if ( n->in(0) == NULL && !n->is_Load() && !n->is_CMove() ) {
2793 cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
2794 sink_list.push(n);
2795 peel >>= n->_idx; // delete n from peel set.
2796 not_peel <<= n->_idx; // add n to not_peel set.
2797 peel_list.remove(i);
2798 incr = false;
2799 #if !defined(PRODUCT)
2800 if (TracePartialPeeling) {
2801 tty->print_cr("sink to not_peeled region: %d newbb: %d",
2802 n->_idx, get_ctrl(n)->_idx);
2803 }
2804 #endif
2805 }
2806 } else {
2807 // Otherwise check for special def-use cases that span
2808 // the peel/not_peel boundary such as bool->if
2809 clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
2810 new_phi_cnt++;
2811 }
2812 }
2813 }
2814 if (incr) i++;
2815 }
2816
2817 if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
2818 #if !defined(PRODUCT)
2819 if (TracePartialPeeling) {
2820 tty->print_cr("\nToo many new phis: %d old %d new cmpi: %c",
2821 new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
2822 }
2823 #endif
2824 if (new_peel_if != NULL) {
2825 remove_cmpi_loop_exit(new_peel_if, loop);
2826 }
2827 // Inhibit more partial peeling on this loop
2828 assert(!head->is_partial_peel_loop(), "not partial peeled");
2829 head->mark_partial_peel_failed();
2830 if (cloned_for_outside_use > 0) {
2831 // Terminate this round of loop opts because
2832 // the graph outside this loop was changed.
2833 C->set_major_progress();
2834 return true;
2835 }
2836 return false;
2837 }
2838
2839 // Step 3: clone loop, retarget control, and insert new phis
2840
2841 // Create new loop head for new phis and to hang
2842 // the nodes being moved (sinked) from the peel region.
2843 LoopNode* new_head = new LoopNode(last_peel, last_peel);
2844 new_head->set_unswitch_count(head->unswitch_count()); // Preserve
2845 _igvn.register_new_node_with_optimizer(new_head);
2846 assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
2847 _igvn.replace_input_of(first_not_peeled, 0, new_head);
2848 set_loop(new_head, loop);
2849 loop->_body.push(new_head);
2850 not_peel.set(new_head->_idx);
2851 set_idom(new_head, last_peel, dom_depth(first_not_peeled));
2852 set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
2853
2854 while (sink_list.size() > 0) {
2855 Node* n = sink_list.pop();
2856 set_ctrl(n, new_head);
2857 }
2858
2859 assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
2860
2861 clone_loop( loop, old_new, dd );
2862
2863 const uint clone_exit_idx = 1;
2864 const uint orig_exit_idx = 2;
2865 assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
2866
2867 Node* head_clone = old_new[head->_idx];
2868 LoopNode* new_head_clone = old_new[new_head->_idx]->as_Loop();
2869 Node* orig_tail_clone = head_clone->in(2);
2870
2871 // Add phi if "def" node is in peel set and "use" is not
2872
2873 for(i = 0; i < peel_list.size(); i++ ) {
2874 Node *def = peel_list.at(i);
2875 if (!def->is_CFG()) {
2876 for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2877 Node *use = def->fast_out(j);
2878 if (has_node(use) && use->in(0) != C->top() &&
2879 (!peel.test(use->_idx) ||
2880 (use->is_Phi() && use->in(0) == head)) ) {
2881 worklist.push(use);
2882 }
2883 }
2884 while( worklist.size() ) {
2885 Node *use = worklist.pop();
2886 for (uint j = 1; j < use->req(); j++) {
2887 Node* n = use->in(j);
2888 if (n == def) {
2889
2890 // "def" is in peel set, "use" is not in peel set
2891 // or "use" is in the entry boundary (a phi) of the peel set
2892
2893 Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
2894
2895 if ( loop->is_member(get_loop( use_c )) ) {
2896 // use is in loop
2897 if (old_new[use->_idx] != NULL) { // null for dead code
2898 Node* use_clone = old_new[use->_idx];
2899 _igvn.replace_input_of(use, j, C->top());
2900 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
2901 }
2902 } else {
2903 assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
2904 // use is not in the loop, check if the live range includes the cut
2905 Node* lp_if = use_c->in(orig_exit_idx)->in(0);
2906 if (not_peel.test(lp_if->_idx)) {
2907 assert(j == orig_exit_idx, "use from original loop");
2908 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
2909 }
2910 }
2911 }
2912 }
2913 }
2914 }
2915 }
2916
2917 // Step 3b: retarget control
2918
2919 // Redirect control to the new loop head if a cloned node in
2920 // the not_peeled region has control that points into the peeled region.
2921 // This necessary because the cloned peeled region will be outside
2922 // the loop.
2923 // from to
2924 // cloned-peeled <---+
2925 // new_head_clone: | <--+
2926 // cloned-not_peeled in(0) in(0)
2927 // orig-peeled
2928
2929 for(i = 0; i < loop->_body.size(); i++ ) {
2930 Node *n = loop->_body.at(i);
2931 if (!n->is_CFG() && n->in(0) != NULL &&
2932 not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
2933 Node* n_clone = old_new[n->_idx];
2934 _igvn.replace_input_of(n_clone, 0, new_head_clone);
2935 }
2936 }
2937
2938 // Backedge of the surviving new_head (the clone) is original last_peel
2939 _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
2940
2941 // Cut first node in original not_peel set
2942 _igvn.rehash_node_delayed(new_head); // Multiple edge updates:
2943 new_head->set_req(LoopNode::EntryControl, C->top()); // use rehash_node_delayed / set_req instead of
2944 new_head->set_req(LoopNode::LoopBackControl, C->top()); // multiple replace_input_of calls
2945
2946 // Copy head_clone back-branch info to original head
2947 // and remove original head's loop entry and
2948 // clone head's back-branch
2949 _igvn.rehash_node_delayed(head); // Multiple edge updates
2950 head->set_req(LoopNode::EntryControl, head_clone->in(LoopNode::LoopBackControl));
2951 head->set_req(LoopNode::LoopBackControl, C->top());
2952 _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
2953
2954 // Similarly modify the phis
2955 for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
2956 Node* use = head->fast_out(k);
2957 if (use->is_Phi() && use->outcnt() > 0) {
2958 Node* use_clone = old_new[use->_idx];
2959 _igvn.rehash_node_delayed(use); // Multiple edge updates
2960 use->set_req(LoopNode::EntryControl, use_clone->in(LoopNode::LoopBackControl));
2961 use->set_req(LoopNode::LoopBackControl, C->top());
2962 _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
2963 }
2964 }
2965
2966 // Step 4: update dominator tree and dominator depth
2967
2968 set_idom(head, orig_tail_clone, dd);
2969 recompute_dom_depth();
2970
2971 // Inhibit more partial peeling on this loop
2972 new_head_clone->set_partial_peel_loop();
2973 C->set_major_progress();
2974 loop->record_for_igvn();
2975
2976 #if !defined(PRODUCT)
2977 if (TracePartialPeeling) {
2978 tty->print_cr("\nafter partial peel one iteration");
2979 Node_List wl(area);
2980 Node* t = last_peel;
2981 while (true) {
2982 wl.push(t);
2983 if (t == head_clone) break;
2984 t = idom(t);
2985 }
2986 while (wl.size() > 0) {
2987 Node* tt = wl.pop();
2988 if (tt == head) tty->print_cr("orig head");
2989 else if (tt == new_head_clone) tty->print_cr("new head");
2990 else if (tt == head_clone) tty->print_cr("clone head");
2991 tt->dump();
2992 }
2993 }
2994 #endif
2995 return true;
2996 }
2997
2998 //------------------------------reorg_offsets----------------------------------
2999 // Reorganize offset computations to lower register pressure. Mostly
3000 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3001 // then alive with the post-incremented trip counter forcing an extra
3002 // register move)
3003 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3004 // Perform it only for canonical counted loops.
3005 // Loop's shape could be messed up by iteration_split_impl.
3006 if (!loop->_head->is_CountedLoop())
3007 return;
3008 if (!loop->_head->as_Loop()->is_valid_counted_loop())
3009 return;
3010
3011 CountedLoopNode *cl = loop->_head->as_CountedLoop();
3012 CountedLoopEndNode *cle = cl->loopexit();
3013 Node *exit = cle->proj_out(false);
3014 Node *phi = cl->phi();
3015
3016 // Check for the special case of folks using the pre-incremented
3017 // trip-counter on the fall-out path (forces the pre-incremented
3018 // and post-incremented trip counter to be live at the same time).
3019 // Fix this by adjusting to use the post-increment trip counter.
3020
3021 bool progress = true;
3022 while (progress) {
3023 progress = false;
3024 for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3025 Node* use = phi->fast_out(i); // User of trip-counter
3026 if (!has_ctrl(use)) continue;
3027 Node *u_ctrl = get_ctrl(use);
3028 if (use->is_Phi()) {
3029 u_ctrl = NULL;
3030 for (uint j = 1; j < use->req(); j++)
3031 if (use->in(j) == phi)
3032 u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3033 }
3034 IdealLoopTree *u_loop = get_loop(u_ctrl);
3035 // Look for loop-invariant use
3036 if (u_loop == loop) continue;
3037 if (loop->is_member(u_loop)) continue;
3038 // Check that use is live out the bottom. Assuming the trip-counter
3039 // update is right at the bottom, uses of of the loop middle are ok.
3040 if (dom_lca(exit, u_ctrl) != exit) continue;
3041 // Hit! Refactor use to use the post-incremented tripcounter.
3042 // Compute a post-increment tripcounter.
3043 Node *opaq = new Opaque2Node( C, cle->incr() );
3044 register_new_node(opaq, exit);
3045 Node *neg_stride = _igvn.intcon(-cle->stride_con());
3046 set_ctrl(neg_stride, C->root());
3047 Node *post = new AddINode( opaq, neg_stride);
3048 register_new_node(post, exit);
3049 _igvn.rehash_node_delayed(use);
3050 for (uint j = 1; j < use->req(); j++) {
3051 if (use->in(j) == phi)
3052 use->set_req(j, post);
3053 }
3054 // Since DU info changed, rerun loop
3055 progress = true;
3056 break;
3057 }
3058 }
3059
3060 }